In this video, I'm explaining the difference between "bonjour" and "bonsoir". Both are used to greet people but not a the same time of the day. Say "Bonjour" until the end of the afternoon and "bonsoir" once the evening starts. Bonjour is a greeting and only a greeting at the difference of "bonsoir" that can be used to say good bye in the evening and evening ONLY.
"Bonjour" means "hello", right? Why can't you say it at night?