Hello, I'm 'The French' (I'm not a teacher but I try to help you) I don't understand why you are confuse.
You have learn the eight or nine parts of speech, and for me it's clear.
I try to explain what I have learn:
Nouns are things animate or unnanimate (table,dog, cat, horse, chair, sofa, bed) or people (Susan, Bill..).
Verbs show us what the subject is doing or it state.
I give you my example:
I am running. (you have the subject I, and a main verb that show the action of the subject I; the subject is running now).
I am tired. (The same I subject, verb tired, that show the state of I).
Perhaps is it the progressive form that blocks you?
Have a nice day.