His and hers and the possesive pronouns.
"her" addresses a person, but not as a possesive.
Now saying "his" or "hers" is possesive.
For Example,
"That basketball is his." or "That controller is hers."
Now it is possible to use "her" as a possesive trait but the word itself does not descrive possesion, therefor it cannot be considered a possesive pronoun.
Hope this helps and have a nice day.
-Kaikai Kitan