It can be used in different contexts:
* "Boy" - It's a general term for a young male, but it's not as common in everyday speech as it used to be.
* "Waiter" - This is the most common usage in restaurants, especially in more traditional establishments. You'll hear "Garçon!" called out to get a waiter's attention.
The word "garçon" is masculine. The feminine equivalent is "fille".