勇气(yǒng qì) - courage, bravery, nerve in Mandarin

勇气 (yǒng qì) is courage as a quantity you have or lack, which is why it pairs with verbs of having and losing: 有勇气, 没有勇气, 失去勇气. The set phrase to learn is 鼓起勇气, to work up or pluck up the courage, and it takes the same shape as the English idiom.

Do not mix it with 勇敢 (yǒng gǎn), which is the adjective brave. 他很勇敢 describes the person; 他有勇气 says he has the thing needed for a particular act. Saying 他很勇气 is the single most common mistake here, and it is ungrammatical.

The 气 in this word is the same 气 as in 生气 and 客气: not air, but a state of spirit. Recognising that sense makes a whole family of words open up at once.