Ce soir means “this evening” or “tonight” in French.
Soir is “evening” and ce means “this”.
You may be wondering why a word that’s related to the evening also stands in for “tonight”. That’s because the French are very specific – often, terms dealing with the night have to do with sleep or the end of an evening out, as with Bonne nuit (“Goodnight”, as in you’re going to bed) versus Bonne soirée (Have a nice evening/night.)
You’ll often hear À ce soir ! – “See you tonight!”