The book is 'hers'. [=the book belongs to her; it is her book]
a former professor 'of hers' [=one of her former professors]
That face 'of hers' [=her face] is hard to forget.
(..) She once gave me a castle and a wife, then rectified me right out of them. That was Ser Jaime's doing, not hers. When Queen Cersei wants something, she pays in advance and in gold. Several chests of it, in fact. (..)2019 TvShow: Game of Thrones Title: Winterfell Season: 8 Episode 1