good evening / good night
In French there are to common expressions for greeting each other: bonjour - good morning, good afternoon and bonsoir - good evening, goodnight.
Si in French the day is separated into two parts from the point of view of greeting: if it is day, they use bonjour, if it is dark they say bonsoir. In the evening or at night they use bonsoir even for leaving. The synonym for English Goodnight is used only by the members of family or other people living together before going to bed.
Hope I could help