These have no plural. The following are common nouns that are usually uncountable:
– accomodation, advice, behavior, bread, copper (and all other metals), meat, sugar, English (and all other languages), furniture, health, information, knowledge, luggage, maths (and other school subjects), news, progress, research, rice (and all other grains and cereals), salt (and all other condiments, e.g. pepper), scenery, spaghetti, traffic, transport, travel, trouble, water (and all other liquids), weather, work.
Use a slice, a lump, and a piece with uncountable nouns for food.
– Just one lump of sugar, please.
– I’ll just have a small slice of cake.
– Would you like another piece of toast?
Nouns which can be countable or uncountable
1. Nouns we can think of as a single thing or substance
– e.g. chicken, chocolate, egg, hair, iron, paper, stone.
– There are only two chocolates left in the box.
– You’ve got chocolate on your T-shirt.
– We’ll have to buy a new iron.
– Green vegetables are rich in iron.
– Have you read today’s paper?
– I need to go and buy some paper for the printer.
– There’s a hair in my soup.
– She’s got short dark hair.
– The house is built of stone. (= rock)
– The necklace is made of semi-precious stones. (= gems)
2. Nouns which are used to refer to particular varieties
– e.g. wine, country.
– Would you like some wine? This is a very good wine.
– I’d like to have a house in the country. He’s worked in five different countries.
3. Words for some drinks
– e.g. coffee, beer.
The countable noun means a glass of, a cup of, a bottle of.
– Coffee is produced in Africa and South America.
– Shall we have a coffee and a piece of cake?
4. Time, space, room
– There’s no time to talk – we have to rush!
– I didn’t have a very good time at the party.
– There’s no space left. You’ll have to get another bag.
– Fill in the spaces with the correct preposition.
– There’s room for seven people in this car.
– This is my favorite room in the whole house.