1) Countable nouns are for things we can count.
2) Uncountable nouns are for the things we can not count.
3) Uncountable nouns are also used for abstract nouns.They are used with a singular verb. They usually do not have a plural form.
Uncountable nouns do not take a/an before them. To express a quantity of one of these nouns, we use the expressions: some, a bit of, a piece of, a lot of...
A- Have you got any money in your wallet?
B- Yes, I think I've got some money...
4)We use How much...? with uncountable nouns.
A- How much rice is there?
B- There isn't much rice.
We use How many...? with countable nouns.
A- How many books are in the library?
B- There aren't many books.