Note: 'Hers' is a third person possessive pronoun.
1.
You use hers to indicate that something belongs or relates to a woman, girl, or female animal.
His hand as it shook hers was warm and firm...
He'd never seen eyes as green as hers...
Professor Camm was a great friend of hers...
PRON
2.
In written English, hers is sometimes used to refer to a person without saying whether that person is a man or a woman. Some people dislike this use and prefer to use 'his or hers' or 'theirs'.
The author can report other people's results which more or less agree with hers.
PRON
3.
Hers is sometimes used to refer to a country or nation. (FORMAL or WRITTEN)
PRON