head
The German word 'Kopf' is used to refer to the head of a person or animal. It can also be used metaphorically, for example, in phrases like 'Kopf hoch' (meaning 'chin up') to encourage someone to stay positive. In German, 'Kopf' is a masculine noun.
She has a clear head.
This phrase is used to describe someone who is thinking clearly or rationally. It's the equivalent of the English phrase 'She has a clear head'. 'Kopf' in German means 'head' and 'klar' can mean 'clear' or 'clean', so a literal translation could be 'She has a clean head'.
He doesn't lose his head.
This phrase means that the person keeps calm even in difficult situations. It corresponds to the English phrase 'He doesn't lose his head'. The word 'Kopf' in German means 'head' and 'verliert' means 'loses', so the literal translation would be 'He doesn't lose the head'.