"Хана" is a slang noun. The nearest meaning in classical English is "end". "Нам хана" can be translated as "this is the end (for us)". Also "тебе хана" can be used as a light threat: you are in deep trouble! It's hard to explain, but "хана" also contains a bit of humor. It makes "хана" a bit funny and not so serious. ))
Hi dude, it means - there is no way to stay alive.
But usually it's used to emphasize that we did something wrong and somebody will kill us.