Here "blood" represents the person who was killed. An "avenger of blood" is a close relative of the person who was killed. This relative is responsible for punishing the murderer. (See: [[rc://en/ta/man/translate/figs-metonymy]])
# the one who took a life
This is an idiom. AT: "the one who killed the other person" (See: [[rc://en/ta/man/translate/figs-idiom]])
# in the heat of his anger
Someone being very angry is spoken of as if anger were something that could become hot. AT: "and being very angry" (See: [[rc://en/ta/man/translate/figs-metaphor]])
# strike him and kill him
"And the blood avenger strikes and kills the one who had killed the other person"
# though that man did not deserve to die, since he had not hated his neighbor in the past