C417 tip of sword

I don't understand Mr. Zhao's words. Killing is killing, how can it be to save someone?

Mr. Zhao patted Xia Xin, who was meditating on the ground, whose body was riddled with scars, and said, "This person is Xia Xin's body."

He then pointed at the corpse inside the coffin, "Although that person has Xia Xin's face, she is Little He's body