A noncount (or mass) noun refers to something that cannot be counted. Noncount nouns are normally not used after the words a or an or after a number. They have only one form and are used with singular verb forms.
The rain is still coming down heavily.
The information was unclear.
Her despair now seems even deeper.
A few noncount nouns look like plurals but are used with the singular form of verbs.
Physics was my favorite course.
My mother studied economics when she was in college.
The news that morning was good.
Gerunds, which are nouns that are identical to the -ing form of a verb (the present participle), are also noncount nouns.
I think I've been doing too much running.
Her crying made me sad.
A particular noun can be count or noncount depending on its meaning in a particular context.
I’ve read that book several times. (count)
Time seemed to stop when he entered the room. (noncount)
Don't drink too much coffee. (noncount)
(to a waiter) Can we have two coffees please? (count)