What does Leviticus 16:18 mean?

Then he goes out to the altar in front of the tent and makes it right too. He takes some of the bull’s and goat’s blood and puts it on the horns at the corners of the altar. Leviticus 16:18 - Modern Text Bible

(Even the altar, the place where sacrifices are made, needs to be cleansed because it’s touched by the people’s sin.)