Well, his heart stopped, and he stopped breathing. He was technically dead, but they managed to resuscitate him quickly. It was a lot more than a faint.
As for whether he'll play again, we don't know until the medical investigations are complete. Even then, there is the question of whether the relevant authorities would let him play, when there is obviously the chance of this happening again with a much worse outcome. A UK doctor has said that if Eriksen were still contracted in England, then they wouldn't let him play again. It's entirely understandable.

Let's just hope he recovers fully and this doesn't happen again.