PRONOUNS represent regular nouns. They are a very small group.
The SUBJECT does the action. SUBJECTS come BEFORE (to the left of) the VERB.
The OBJECT receives the action. OBJECTS come AFTER (to the right of) the VERB or prepositins (In, on, from, by, to, etc)
SUBJECT PRONOUNS are I, you, he/she/it, we, they. (they do the action)
OBJECT PRONOUNS are me, you, him/her/it, us, them. (they receive the action)