This can be stated in active form. AT: "You must certainly put to death anyone who kills another person" (See: [[rc://en/ta/man/translate/figs-activepassive]])
This is an idiom that means that one life would replace the other. AT: "one life to replace the other life" or "to replace the one that he killed" (See: [[rc://en/ta/man/translate/figs-idiom]])