Definition :-
A pronoun (I, me, he, she, herself, you, it, that, they, each, few, many, who, whoever, whose, someone, everybody, etc.) is a word that takes the place of a noun. In the sentence Tom met Jane, and he spoke to her. - the pronouns he and her take the place of Tom and Jane, respectively. There are four types of pronouns: subject (for example, he); object (him); possessive (his), or reflexive (himself).
Subject Pronouns are used when the pronoun is the subject of the sentence. You can remember subject pronouns easily by filling in the blank subject space for a simple sentence.

Example: ___ did the job.
I, he, she, we, they, who, whoever, etc., all qualify and are, therefore, subject pronouns.
Object Pronouns are used when the pronoun is the object of the sentence. In this case the sentence has a noun or another pronoun as a subject.
Example: He talked to _____
Me, us, you, him, her, them, all qualify as object pronouns.

Possessive Pronouns indicate possession of a particular thing. In most case possessive pronouns are placed before nouns.
Example: We travelled to the station in ______ car
My, our, your, his, her, their, all qualify as possessive pronouns.

A Reflexive Pronoun is a special kind of pronoun. It is usually used when the object of a sentence is the same as the subject.
Example: I / We did all the work myself/ourselves.
Myself, ourselves, yourself, yourselves, himself, herself, themselves, all qualify as reflexive pronouns.