Some nouns can be both countable and uncountable, usually with a different meaning for each. This page lists the most common such nouns. 

accommodation

uncountable:  a place to live in or stay at
countable:  an agreement between opposing people or organisations

aid

uncountable:  money or help given to those who need it
countable:  something that helps you to do something

air

uncountable:  the mixture of gases surrounding the earth
countable:  (old-fashioned) a tune or a melody

art

uncountable:  paintings, sculpture, drawings, etc.
countable:  an activity that needs special training or knowledge

ballet

uncountable:  a style of dancing that tells a story
countable:  a particular work of classical dance

beauty

uncountable:  the quality that makes someone or something beautiful
countable:  a beautiful woman, or an excellent thing

beer

uncountable:  an alcoholic drink made with malt and hops
countable:  a glass of beer

blood

uncountable:  the red liquid inside our bodies
countable:  (old-fashioned) a rich man who likes to show off

bread

uncountable:  a common food that's made from wheat or other grains
countable:  a particular variety or type of bread

business

uncountable:  the activity of making, buying or selling things for money
countable:  a particular company or other commercial organisation

cheese

uncountable:  a solid dairy food
countable:  a particular kind or variety of cheese

cinema

uncountable:  the making and marketing of films and movies
countable:  a place in which films are shown on a big screen ("movie theater" is more common in American English)

coffee

uncountable:  a drink made with ground, roasted seeds
countable:  one cup of coffee

currency

uncountable:  the banknotes and coins used in a country
countable:  the monetary unit of a particular country

danger

uncountable:  the possibility of something very bad happening
countable:  a person or thing that can harm or kill

delight

uncountable:  a feeling of great happiness
countable:  something or someone that makes us happy

depression

uncountable:  a feeling of great sadness that can require medical treatment to cure
countable:  a period of little economic activity when many people lose their jobs

dessert

uncountable:  sweet food eaten at the end of a meal
countable:  a particular type or category of dessert

distribution

uncountable:  the transportation and delivery of goods to shops and buyers
countable:  the geographic range of a species, a language, a disease, etc.

employment

uncountable:  the giving of work to someone, or the state of having work
countable:  an exchange of labour for payment, usually under contract

enjoyment

uncountable:  the pleasure you get from something
countable:  an activity or experience that gives pleasure

entertainment

uncountable:  films, concerts, sports, TV shows, etc. that an audience can enjoy
countable:  a particular performance or activity that people enjoy

failure

uncountable:  lack of success in doing something
countable:  a person or thing that is not successful

faith

uncountable:  strong belief in someone or something
countable:  a particular religion

food

uncountable:  things that people or animals eat
countable:  a particular type or category of food

freedom

uncountable:  the state of being free to do what you want
countable:  the right to do what you want to do

fruit

uncountable:  food that contains seeds, like apples, oranges, pears, etc.
countable:  a particular kind or category of fruit

fuel

uncountable:  something that's burned for heat or power, like wood, oil, gas, etc.
countable:  a particular kind of fuel

gas

uncountable:  any substance like air that's neither solid nor liquid
countable:  a particular type of gas

glass

uncountable:  the material used to make windows, bottles, fishbowls, etc.
countable:  a drinking vessel made of glass

gold

uncountable:  a valuable metal that's used to make jewellery
countable:  a gold medal, or a colour that's similar to gold

gossip

uncountable:  stories about other people's private lives, often untrue or exaggerated
countable:  a person who likes telling and hearing gossip

grammar

uncountable:  the rules of a language
countable:  a book that describes the rules of a language

grass

uncountable:  a common plant that's eaten by horses, cows, sheep, etc.
countable:  any particular type of grass

ground

uncountable:  the surface of the Earth
countable:  an area of land used for a particular purpose

hair

uncountable:  the mass of fibres on your head
countable:  a single strand of hair

heat

uncountable:  the quality of being hot
countable:  a qualifying race or game at the start of a competition

height

uncountable:  how high something is, or how tall someone is
countable:  a high place or position

ice cream

uncountable:  a sweet frozen food made from milk
countable:  a small amount of ice cream on a stick, in a cone, or in a small container

injustice

uncountable:  unfair treatment or mistaken legal judgement
countable:  a particular action, judgement or situation that's unfair

intelligence

uncountable:  the ability to understand and think about complex ideas
countable:  a particular type or class of intelligence

iron

uncountable:  a strong, hard metal
countable:  a household appliance for smoothing out wrinkles in clothes

irony

uncountable:  humour in which someone says the opposite of what they really mean
countable:  an event or situation that involves a contradiction of some sort

jam

uncountable:  sweet food that's made from fruit and usually spread on bread or toast
countable:  many vehicles stuck together in traffic, or a difficult situation

jealousy

uncountable:  unhappiness felt when you think someone you like wants somebody else, or when someone else has something you want
countable:  an action or comment that shows jealousy

joy

uncountable:  a feeling of great happiness
countable:  something that makes you feel very happy

juice

uncountable:  liquid that's squeezed from fruit or vegetables
countable:  one glass of juice, or a particular kind of juice

kindness

uncountable:  the quality of being kind to people or animals
countable:  a kind act

land

uncountable:  the earth's surface, or part of this surface
countable:  a country or region

love

uncountable:  a strong affection for someone
countable:  a person, thing or activity that you love

marble

uncountable:  a type of stone often used in buildings
countable:  a small glass ball used for playing games

meat

uncountable:  animal or bird flesh eaten as food
countable:  a particular type of meat

metal

uncountable:  a solid material that can be mined, like iron, tin, gold, etc.
countable:  a particular kind or category of metal

nature

uncountable:  all living things and the habitats that sustain them
countable:  the basic character of a person or an animal, or a basic feature of something

noise

uncountable:  loud or unpleasant sound
countable:  a particular sound

oil

uncountable:  a thick liquid, such as the dark liquid from underground that's used to make fuel, or a thick liquid that's used for cooking food
countable:  a particular type of oil

paper

uncountable:  a material that's used for writing on, printing on, or wrapping things in
countable:  a newspaper

passion

uncountable:  very strong feeling or emotion
countable:  a very strong interest in something or someone

power

uncountable:  the ability to control people, places or things
countable:  a country with a lot of political, economic or military power

pride

uncountable:  positive emotion felt when you or someone you know achieves something special
countable:  a group of lions

production

uncountable:  the process of making or growing things
countable:  a film, play, television or radio programme

pronunciation

uncountable:  the sounds made when speaking a language or saying a word
countable:  a particular way of pronouncing a word or a language

quality

uncountable:  the standard of something, or how good it is
countable:  a particular feature of someone or something

quantity

uncountable:  the amount of something
countable:  a particular amount of something or number of things

room

uncountable:  the space needed for something
countable:  a space inside a building with walls, a floor and a ceiling

salad

uncountable:  raw vegetables like lettuce, tomato, cucumber, etc. mixed together
countable:  one serving of salad, or a particular type of salad

satire

uncountable:  humour used to criticize someone or something
countable:  a movie, book, play, etc. that uses satirical humour

silence

uncountable:  total quiet, or no sound at all
countable:  a period of time when nobody's speaking

sleep

uncountable:  a natural state of rest
countable:  a particular period of sleep

smoke

uncountable:  clouds that rise from fires, chimneys, etc.
countable:  a cigarette, or the act of smoking

soil

uncountable:  the top layer of earth in which plants can grow
countable:  a particular type or category of soil

sorrow

uncountable:  a feeling of great sadness
countable:  an event that causes great sadness

space

uncountable:  empty area, or the unused part of something
countable:  a particular area that has nothing in it

speed

uncountable:  how fast something or someone moves
countable:  a particular speed

spelling

uncountable:  the ordering of letters to form a word
countable:  a particular way of spelling a word

sport

uncountable:  physical activities in which players compete individually or in teams
countable:  a particular kind of sport

strength

uncountable:  physical power, or how strong someone or something is
countable:  an important ability or feature

success

uncountable:  the achievement of a goal
countable:  a successful person, event or result

sugar

uncountable:  sweet crystals added to drinks like tea and coffee
countable:  one teaspoon of sugar, or a particular type of sugar

tea

uncountable:  a drink made by adding boiling water to dried plant parts
countable:  one cup of tea, or a particular type of tea

time

uncountable:  duration as measured by clocks
countable:  a particular occasion or time when something happened

toast

uncountable:  sliced bread that's been heated and browned in a toaster
countable:  the act of drinking to someone's happiness or success

trade

uncountable:  the buying and selling of goods and services
countable:  a type of skilled work, or a particular type of business

trust

uncountable:  the belief that someone or something is honest or won't cheat you
countable:  a legal arrangement or organization that manages someone's money or property

understanding

uncountable:  comprehension of the facts about something, or comprehension of someone's situation or feelings
countable:  an informal agreement

usage

uncountable:  the way that words are used in spoken or written language
countable:  a particular meaning or usage of a word

vision

uncountable:  the sense of sight, or the ability to see
countable:  an idea of what the future could be like

weight

uncountable:  how heavy someone or something is
countable:  a heavy object that's used to build muscle mass and strength

whisky

uncountable:  a strong alcoholic drink
countable:  one glass of whisky

width

uncountable:  how wide something is
countable:  a measured piece of cloth, or the width of a swimming pool

wine

uncountable:  an alcoholic drink made from grapes, or a similar drink made from rice, elderberries, etc.
countable:  a glass of wine, or a particular type of wine

wood

uncountable:  the hard material in trees
countable:  a particular type of wood

work

uncountable:  a job done for money, or any productive activity
countable:  something created by a writer, painter, musician, or other artist

youth

uncountable:  the time in someone's life when they're young
countable:  a young man

sources : Original Link