hers

The book is hers. [=the book belongs to her; it is her book]这本书是她的。

Hers is the book on the left. [=her book is the one on the left]左边这本书是她的。

a former professor of hers [=one of her former professors]曾教过她的一位教授

That face of hers [=her face] is hard to forget.她那张脸让人很难忘记。

Let's go back to hers for a drink.咱们回她家喝一杯。