"Has fallen asleep" is an idiom that means "has begun to sleep" or "is sleeping." Jesus meant that Lazarus had died, but the disciples did not understand this. So it is important to keep the idea of sleeping in the translation. (See: [[rc://en/ta/man/translate/figs-idiom]])
"Wake him out of sleep" is an idiom that means "cause someoen who is sleeping to wake up." Jesus meant that he was going to bring Lazurus back to life. But his disciples did not understand this. So it is important to keep the idea of waking him up in the translation. Alternate translation: "but I am going there to wake him up" (See: [[rc://en/ta/man/translate/figs-idiom]])