A pimp is someone who employs prostitutes — they work for the pimp, who gets a cut of their money. He pimps them.
Pimp is a word that has greatly shifted in meaning, as it sometimes means "great" or "cool," as in "That bike is pimp!" However, that's a slang meaning that many people, especially adults, won't understand or like. The main meaning of pimp as the boss of prostitutes is pretty creepy, because prostitution is illegal and pimps are not known for treating their workers very nicely. For some reason, pimps are known for their flashy dress.
