What does Leviticus 4:18 mean?

Then the priest will dip his finger in the blood and put some of it on the horns at the corners of the altar that stands before the Lord in the tent. He’ll pour out the rest of the blood at the base of the altar where burnt offerings go. Leviticus 4:18 - Modern Text Bible

(This describes the priest’s ritual for dealing with sin—using blood as a symbol of cleansing and dedicating the altar to God.)