“And Aaron lifted up his hands toward the people and blessed them.”
What does it mean when someone you respect blesses you? Do we think that G_d has blessed us? We believe that G_d taught Moses and Moses taught Aaron, so actually we are being blessed by G_d.
Having this “blessing” might make us behave better, or to do something with more confidence. We give “blessings” to someone doing something with which we don't quite agree. “I know you don't agree with me, mom and dad, but will you give me your blessing?” “Yes, my son.”