A man who has no hair is

pelo

calvo

seguro

negro

Answer: Calvo

Explanation:

Calvo is bald, someone who doesn't have hair. Pelo is hair, which doesn't match with the question. Seguro is insurance, which doesn't have anything to do with hair. The last one, negro is black, and this doesn't have anything to do with hair, color wise or race wise, unless you would describe the person further. For example, "Un hombre calvo que es negro".

Espero que esto ayude, que tengan un día bendecido y maravilloso! : -)