This is the 3153rd most frequent Japanese word.
勇
Bravery; courage.
勇気 (courage)
彼の勇気がなければ、私たちの計画は成功しなかったでしょう。
If it weren't for his courage, our plan wouldn't have succeeded.
勇敢 (bravely)
彼女はその状況で勇敢に振る舞った。
She behaved bravely in that situation.
勇者 (hero)