Yom Kippur and Atonement

“And the LORD spoke to Moses, saying, “Now on the tenth day of this seventh month is the Day of Atonement. It shall be for you a time of holy convocation, and you shall afflict yourselves and present a food offering to the LORD. And you shall not do any work on that very day, for it is a Day of Atonement, to make atonement for you before the LORD your God.” (Leviticus 23:26-29)

One for Israel explains the holiest day of the year.

https://www.youtube.com/watch?v=zUvnxM0MM20