What does subject pronoun and object pronoun?

A subject pronoun is a pronoun that is used only as the subject of a sentence or a clause. The subject personal pronouns are: I, we, he, she, they.

An object pronoun is a pronoun that is used only as the object of a verb or a preposition. The object personal pronouns are: me, us, him, her, them.

Note: The personal pronouns you and it can function as a subject pronoun or an object pronoun.

Examples:

I had a good time at the party. Thank you for inviting me.

We had a good time at the party. Thank you for inviting us.

You have a new hairstyle. It looks good on you. I like it.

He was at the mall so I stopped to speak to him.

She was at the mall so I stopped to speak to her.

They were at the mall so I stopped to speak to them.