He hype, and acting live, like on camera or like he a gangster and ready to do something. But as so I the cameras stop rolling he gonna stop, but off air is also meaning stop his breathing.

Since Key Loads' alter ego is Jason Vorhees, we all know Freddy could only beat Jason in the dreamworld, in his nightmares. So what Keys is saying is, he came out of nightmares ready for all rappers, and the only way they will beat him, is in their dreams.