"Fine, good night."
Dobrze: /ˈdɔb.ʐɛ/ Adverb: Well, OK, Fine, Alright, Good
Dobranoc: /dɔˈbra.nɔt͡s/ • Dobra + Noc /dɔˈbra.nɔt͡s/ f ♀ • Interjection - Good Night • Departing Farewell and bedtime Sleep Well wish • not a nocturnal Greeting like: [ Dobry Wieczór: /ˈdɔ.brɨ ˈvʲɛ.t͡ʂur/ m ♂ • Ancient Greek: ἕσπερος: hésperos , Latin: Vesper
Firstly, because "dobry" is an adjective, while in Polish in such situations we use adverbs (dobrze=well). In general Polish is more picky if it comes to adverbs vs adjectives usage, for example in English you would say "I look good" or "I feel good", but in Polish only "I look well" or "I feel well" are possible.
Secondly, and somewhat contradictory to what I've just said, people sometimes say "dobra" (feminine version of "dobry") instead of "dobrze". I guess it's some kind of an exception.