We use the WH question Whose to identify the owner of an object:
A: Whose is this cell phone?
B: This cell phone is Sebastian’s, but this cell phone is mine.
A: Whose jacket is this?
B: It’s Celis’s, but this jacket is ++mine**.
We use possessive pronouns to refer to the owner of an object:
I - Mine: Yesika’s cell phone is Android, mine is Apple.
You - Yours: My jacket is black, yours is red.
He - His: Her books are about cooking, his about cars.
She - Hers: Sebastian’s computer is Mac, hers is HP.
It - Its
We - Ours
They - Theirs