It can be used to refer to:
* A period of time off from work or school: "J'ai hâte de partir en vacances!" (I'm looking forward to going on vacation!)
* A specific holiday or festival: "Les vacances de Noël" (The Christmas holidays)
* A longer period of time spent traveling or relaxing: "Nous allons passer nos vacances en Italie." (We are going to spend our vacation in Italy.)
The context will usually make it clear which meaning is intended.