What’s the difference between hers and her’s?
Hers is the third person singular feminine possessive pronoun – it replaces her + noun.
Though you may see her’s written even by native speakers, it is incorrect. Hers should never have an apostrophe.
The Bottom Line
The idea that hers needs an apostrophe comes out of the fact that on virtually every other word, ‘s indicates possession, so English speakers sometimes think hers should be spelled her’s. However, this is always incorrect – hers is the only correct spelling.