* Possessive pronoun: It translates to "his", "her", or "its" and refers to something belonging to a person or thing previously mentioned. For example: "Il a perdu sa clé" (He lost his key).
* Contraction: It's a shortened form of "ça" (that) and "a" (has), meaning "it has". Example: "Sa va" (It's going well).
To understand the exact meaning of "sa" in a sentence, you need to consider the context and the words surrounding it.