That is true. But after goeden is the next word avond. So then al Dutch people say de 'n'. The same as an apple. Nobody says a apple I think. The woman who says goede-avond without 'n' has not the good pronounce. Sorry my Dutch is better than my English. I hope you understand what I mean to say.
How to properly pronounce 'v' in Dutch? Here, on duolingo it sounds more like german 'v', but from what I found on other sites it's really more like english 'v'. And a guy form Belgium I know was quite surpised when I told him that german 'v' is really 'f'. :) So, what's correct way to say it in Dutch?
If you use it as a greeting, it is always one word: 'Goedenavond', you do not write 'goede avond'.
'Goede avond' can be used when you are talking about a 'good evening'.
I hope you have a good evening = Ik hoop dat je een goede avond hebt. I earned 200 euro's this evening, it was a good evening = Ik verdiende 200 euro's deze avond, het was een goede avond.