English: The cookies are free. We have sandwiches for sale.
French: Les biscuits sont gratuits. Nous avons des sandwichs à vendre.
Of course, what you have to offer to passengers will depend on your airline and what kind of flight you're working. Longer, international flights might serve meals, and shorter continental flights might have food for purchase.
Free (no cost)=gratuit
For sale=à vendre
Want to learn the spoken French you need to work as a flight attendant? Learn even more with Canadian French for Flight Attendants. Special pre-launch trial price for Module 1.