Don't let English be your guide! The English word her has two very different usages: it can be a possessive pronoun, as in Mary lost her book. It can also be an object pronoun, as in Bill saw her. These two usages of her have very distinct translations into ASL: to sign the possessive, you should use the B-handshape, just like other possessive pronouns in ASL. But to translate her in the sentence Bill saw her, you should use a pointing handshape (index finger extended, all other fingers closed into a fist).