This is the 2138th most frequent French word.
cerveau
Brain.
Here, 'cerveau' is used to refer to the physiological organ responsible for cognitive functions.
Le cerveau humain est extrêmement complexe.
The human brain is extremely complex.
In this case, 'cerveau' is used metaphorically to describe someone as intelligent and creative.
Il a beaucoup d'idées brillantes, il est un vrai cerveau.
He has many brilliant ideas, he is a true brain.
The term 'cerveau' is used here to indicate applying mental effort and thinking.