In donne's sonnet what does the phrase one short sleep past mean

It means that death is brief and doesn't last long, like a dream or a nap. He says that death will lose the battle because he might die, but he will live eternally, so death lost and it was nothing more than a short sleep that passes away. It ends with him telling to death that death will die and basically that he wins.

Answer( he"ll) is correct

Have you tried google translate