This means to remove the person from the Christian community and to send him into the world where Satan rules. Alternate translation: "commit this man to Satan by sending him away from the Christian community" (See: [[rc://en/ta/man/translate/figs-metaphor]])
Possible meanings are 1) "flesh" refers to his physical body. Alternate translation: "so that Satan may harm his body" or 2) "flesh" is a metaphor for the sinful nature. Alternate translation: "so that his sinful nature will be destroyed" or "so that he will not continue to live according to his sinful nature" (See: [[rc://en/ta/man/translate/figs-metaphor]])
This can be stated in active form. Alternate translation: "so that God may save his spirit on the day of the Lord" (See: [[rc://en/ta/man/translate/figs-activepassive]])