Countable nouns are individual objects, people, places, etc. which can be counted. For example: books, Italians, pictures, stations, men, etc.
A countable noun can be both singular - a friend, a house, etc. - or plural - a few apples, lots of trees, etc.
You use the singular form of the verb with a singular countable noun. For exmaple: There is an appple on the table. This book is very funny!
You also use the plural form of the verb with a countable noun in the plural. For example: There are some chairs in the classroom. Those apples are very big.
Uncountable nouns are materials, concepts, information, etc. which are not individual objects and can not be counted. For example: information, water, wood, cheese, moeny, etc.
Uncountable nouns are always singular. We use the singular form of the verb with uncountable nouns: For example: There is some milk in the fridge . I need some wood for the fire.
This exercise gives you more practice with countable or uncountable nouns. To to it, click here.