Nouns can be countable or uncountable. Countable nouns can be counted, e.g. an apple, two apples, three apples, etc. Uncountable nouns cannot be counted, e.g. air, rice, water, etc. When you learn a new noun, you should check if it is countable or uncountable and note how it is used in a sentence.
For positive sentences we can use a/an for singular nouns or some for plurals.
There's a man at the door.I have some friends in New York.
For negatives we can use a/an for singular nouns or any for plurals.
Here are some examples of uncountable nouns:
| bread | rice | coffee | information |
| money | advice | luggage | furniture |