Other forms: bon voyages
You can use the expression bon voyage to wish a friend well as she sets off on a trip.
Bon voyage literally means "good voyage" in French, and it can be used as an exclamation, a playful or sophisticated way to send someone off on a journey. You could also throw a bon voyage party, if you were celebrating with a friend who was about to embark on a long trip. English-speakers first began using the expression in the late 1600s.