bonsoir is pronounced something along the lines of 'boh-swahr'. An audio sample is in link.
bonsoir means good eveningBy he way, in this compounded word, bon means good and soir means evening!
"Bonsoir, enchanté(e) de faire votre connaissance."
Bon soir, tu me manques or vous me manquez.
"Good night, sir" in French is "Bonne nuit, monsieur."
That is the correct spelling of the phrase "have a good night." In Spanish, it is "Buenas noches."
"bon jour," "bon soir"
"bonsoir" (written in a single word) is used as one uses 'good evening' in English, as a greeting replacing "bonjour" when you are at the end of the day, or as "good-bye" when you're departing in the evening / the end of the aternoon.
what's good [for diner] tonight? is the translation of 'quoi de bon ce soir'.
Bon soir
Bon Soir!
Bon soir! Merci pour votre... in French means "Good evening! Thank you for your..." in English.