sa

Sa is the feminine singular third-person possessive adjective in French, covering "his", "her" and "its" in one form: sa voiture can be his car, her car or the car of an organisation. Unlike English, French possessives agree with the thing possessed, not the possessor; the gender of the owner is invisible in sa. Context, not grammar, tells you whose car it is.

Like ma and ta, sa swaps to the masculine form son before a vowel or mute h, even when the noun is feminine: son amie (his/her friend), son histoire (his/her story). This is purely phonetic, to avoid the hiatus of sa amie. The plural counterpart for any gender is ses. See the French possessives guide for how the full nine-cell table (three persons by three forms) lines up.