Explain that the literal translation of "bon voyage" is "good journey." Include that it is derived from the French language, but that it is a commonly used expression in English, as well.
Tell them the right context in which to say "bon voyage." It should be said before a person goes on a trip. Although the translation is "good journey," the meaning of the phrase is equivalent to saying "have a good/safe trip."
Add that it can also replace a farewell bid. So instead of saying "goodbye," you can say "bon voyage."
