The form of she used after a preposition, as the object of a verb, or (deprecated) with a conjunction; that woman, that ship, etc.
A female person or animal.
Belonging to a person of unspecified gender (to counterbalance the traditional "his" in this sense).
Belonging to her (belonging to that female, or in poetic or old-fashioned language that ship, city, season, etc).
That which belongs to them; the possessive case of they, used without a following noun.