They washed themselves every time they entered the Meeting Tent. They also washed themselves every time they went near the altar. They did these things like the Lord commanded Moses.
God is in the light (goodness). We should live in the light, too. If we live in the light, then we share fellowship with each other. And when we live in the light, the blood (death) of Jesus cleanses us from all sin. (Jesus is God’s Son.)
But if we confess (admit) our sins, then God will forgive our sins. We can trust God to do this. God does what is right. God will make us clean from all the wrong things we have done.