I accidentally hit send before adding "đúng cảm", and the app suggested I use "gan da." What's the difference?
Dũng cảm is a fully Sino-Vietnamese term so it sounds more formal. Gan dạ is more colloquial and a native term (although the word liver/brave gan is a corruption of 肝 'can').
If I anwser: Đó là một phụ nữ dũng cảm correct?
Pretty much its correct but Duolingo wants you to get used to "nguoi" which is human, so its implying a female human rather than some other species i guess