For it is ignorance. — Rather, for it is a sin of ignorance, or an error. So also at the end of the verse.
Related Commentaries of Numbers 15:25
Numbers 15:25
25 And the priest shall make an atonement for all the congregation of the children of Israel, and it shall be forgiven them; for it is ignorance: and they shall bring their offering, a sacrifice made by fire unto the LORD, and their sin offering before the LORD, for their ignorance: