chico eres un hacha!! la cantas en 3 o 4 idiomas! wow
translate this please
In this context LadyDi's interpretation is probably the correct one, but I have also seen "ser un hacha" used to mean that someone is a hustler, sandbagger, or shark. That is, someone who pretends to be less skillful at something in order to deceive someone else. So it is possible that the speaker was surprised at the listener's polyglot ability, and was jokingly suggesting that he had been led to believe otherwise.
It means, 'Boy you're a genius!! You can sing it in 3 or 4 languages'. This site defines 'hacha' literally as an 'ax' or a 'hatchet' but figuratively as a 'genius'.