He represents the people before God.
As priest, Jesus offered to God the Father the final sacrifice for our sins—His death on the cross.
“Unlike the other high priests, he does not need to offer sacrifices day after day, first for his own sins, and then for the sins of the people. He sacrificed for their sins once for all when he offered himself.” (Hebrews 7:27) http://ow.ly/i/q5Rcg