What are examples of countable nouns?
A noun is countable if it can be used with numbers, so it has both singular and plural form.
Examples of countable nouns
My house is big. - here the noun is used as a singular one.
There are four houses along the street. - here the noun is used as plural together with a number.
I saw a man walking down the street. - here the noun is singular.
Three men were arrested after the protest. - here the noun is used in (irregular) plural form.
Examples of uncountable nouns
There is only little water left in the glass.
The noun water cannot be used with numbers. You can only use words like some, little and much.
Only way to use uncountable nouns with numbers is to add some "units". You cannot say five waters, but it is correct to count bottles, glasses etc. ex. There are 5 littres of water in the tank.