This is the 85th most frequent Vietnamese word.
quyết
"Quyết" means "to decide" or "determined" in English.
In this sentence, 'quyết' is used as part of the verb compound 'quyết định', meaning 'to decide'.
Anh ấy quyết định đi du học.
He decided to study abroad.
Here, 'quyết' means 'to decide' as a standalone verb.
Tôi phải tự quyết điều này.
I must decide this myself.
In this sentence, 'quyết' is part of the noun 'quyết tâm', which means 'determination'.