Count Nouns are things which can be counted. That means that there can be more than one of them. Also, when a count noun is singular and indefinite, the article "a/an" is often used with it. (The real meaning of "a" is "one".) For example: "There are two books on the table."
Non-count nouns are usually things which cannot be counted, such as rice or water. Non-count nouns have a singular form, but when they are indefinite, we either use the word "some" or nothing at all instead of an article. For example: "Could I have some water please?"
Use "How much" for noncount nouns: How much milk can you drink?
Use "How many" for count nouns: How many people are going to the party?
