Pronouns are those words – it, she, him, that, who –  that take the place of a noun or noun phrases. We use a pronoun instead of repeating a noun –  If we didn’t have pronouns, we would find ourselves saying:
Jimmy did not come home. I called Jimmy’s friends. Nobody has seen Jimmy. Yawn.
Use pronouns to replace nouns makes the conversation much easier!
Jimmy did not come home. I called his friends. Nobody has seen him.
his, him

There are three types of pronouns:

Subject pronouns are used when the pronoun refers to the subject in the sentence,  (for example, he, she, it, they).  They are also used if they rename the subject. They will follow to be verbs, such as is, are, was, were, am, will be, had been, etc.
He did not come home,
She was worried, as he did not come home.

Object pronouns are when the word replace the name of the direct object (him, her, me)
Nobody has seen him.

Possessive pronouns (his, theirs)
I called his friends.

how pronouns are used

Demonstrative Pronouns: this, that, these, those  (Here’s a fun read about the pronoun ‘this’.)

Possessive Pronouns indicate ownership Note they do not need apostrophes: mine, yours, his, its, whose.

Interrogative Pronouns – who, what, which…used in sentences that end with a question mark.

Reflexive Pronouns. These are pronouns that end in self or -selves: myself, yourself, himself…

Reciprocal Pronouns – each other, one another

Indefinite Pronouns: another, much, nobody, few, such…

Relative Pronouns  who, whom, which…  (useful rule:  Whom and who are often used incorrectly in sentences.  To understand the difference, instead of who or whom, rephrase the sentence.  If it reads correctly when you use him, write whom,  and if it you can say he instead, write who.

 Pronouns then are those short but very very useful words because we use  pronouns instead of repeating nouns – it, she, him, that, who.  They take the place of a noun or noun phrases.