Through one of them, the Udâna (the out-breathing) leads (us) upwards to the good world by good work, to the bad world by bad work, to the world of men by both.

In plain words: Through one special channel, Udana, the upward breath, carries a person out at death. Good deeds lead to a good world and bad deeds to a bad world. A mix of both leads back to being born as a human.