When you want to say that something belongs to someone. There are different structures we can use.
EXAMPLE
Can you believe I bought a car? It’s mine.
This is my pen. Yours is over there.
His dog is white. Hers is brown.
My cat is black, His is white.
My means of transportation is a motorcycle, his is an electric scooter.
Jane is one of Mary’s cousins.
Jane is a cousin of Mary’s.
Jane is a cousin of hers.
She is one of my co-workers
She is a co-worker of mine.