what are a possessive  forms

Possessive forms tell us who 'possesses' or owns something. We can make the possessive form of most nouns with the use of an apostrophe and 's' or the use of only the apostrophe. For example:
- Sita's book is torn.
- Charles' bag has many books.

Possessive adjectives are : my, your, his, her, its, our, their, whose. For example:
Do not lose my pen.
Whose umbrella is this?

Possessive pronouns are : mine, yours, his, hers, ours, yours, theirs. For example:
This book is mine.
These satchels are theirs.