Literally, “he who has died.” In v. 6 (see comment there) the sinner is represented as a slave. Only death with Christ can release him from his bondage to sin. Paul now illustrates this by pointing to the obvious truth that when a slave dies, he ceases to be subject to the control of his master. So the Christian, when he dies to sin, is free from sin’s control (cf. 1 Peter 4:1).

Literally, “justified from sin.”