A pronoun is a word that replaces a noun.

1. A personal or Subject pronoun is a pronoun that refers to the person speaking, the person spoken to, or the person being spoken about.

The case of a personal pronoun is determined by the function it serves in a sentence.

(i.e.) Mary walked to the store. She bought some milk.

2. Objective pronouns usually receive the action in a sentence.

(i.e.) Mark gave Mary the book. He gave her the book.

3. Possessive adjectives are not pronouns; they modify (not replace) nouns.

(i.e.) (1) It is my book.

4. Possessive pronouns can replace both the noun and its possessive adjective.

Possessive pronouns are different than possessive adjectives, which come before the noun they are modifying. We use possessive pronouns to replace both a noun and its possessive adjective. Possessive pronouns are especially helpful when you want to avoid repeating an object’s name or when it is already clear what you are talking about.

For example, we could say, “That is my book.” This sentence uses a possessive adjective + a noun. Or, if we don’t want to say “book,” we can replace “my book” with a possessive pronoun, as in, “That is mine.”

We also use possessive pronouns to make comparisons. For example, “My car is faster than his.” In this case, we are comparing “my car” to “his car,” but we replace “his car” with the possessive pronoun “his.”

The above definition and usage was retrieved Sept. 12 from https://www.englishbaby.com/lessons/grammar/possessive_pronouns

5. Self-reflexive or Reflexive pronouns are words like myself, yourself, himself, herself, itself, ourselves, yourselves, and themselves. They refer back to a person or thing. We often use reflexive pronouns when the subject and the object of a verb are the same.

(i.e.) She likes to practice by herself.

They enjoy painting by themselves.