"Bon fin de semaine" translates to "have a good weekend", which is a polite expression, while "week-end" refers to the weekend itself.
Here are some ways to use the phrase:
* "Bon week-end!" (Have a good weekend!)
* "J'ai passé un bon week-end." (I had a good weekend.)
* "Je vais au cinéma ce week-end." (I'm going to the movies this weekend.)