Leviticus 5:10

5:10 The second bird he must make a burnt offering according to the standard regulation. So the priest will make atonement on behalf of this person for his sin which he has committed, and he will be forgiven.

Leviticus 5:12

5:12 He must bring it to the priest and the priest must scoop out from it a handful as its memorial portion and offer it up in smoke on the altar on top of the other gifts of the Lord – it is a sin offering.

Leviticus 5:18

5:18 and must bring a flawless ram from the flock, convertible into silver shekels, for a guilt offering to the priest. So the priest will make atonement on his behalf for his error which he committed (although he himself had not known it) and he will be forgiven.