Unlike the sin offering for the priest where no pronouncement is given, Leviticus 4:20 reassures the reader that through this sacrifice, atonement can be made for the nation. Atonement reflects the idea that the sin and guilt of the worshippers have been removed. See commentary on Leviticus 1:4.
20 Thus shall he do with the bull. As he did with the bull of the sin offering, so shall he do with this. And the priest shall make atonement for them, and they shall be forgiven.