Na Man you be! This is Nigerian pidgin English or slang. It depends on how it is being used. if it comes with a question mark, it means the questioner is questioning the masculine ability of the person the question is directed to: but if it ends with a full stop, it is an expression of confirming the masculine ability of the person in question. How to know if it is with a question mark or full stop during a conversation is the tonation.
Na man you be? Na man you be.