The priest is to sacrifice them, one as a sin offering and the other as a burnt offering. In this way the priest will make atonement for the man before the LORD because of his discharge.
KJV
And the priest shall offer them, the one [for] a sin offering, and the other [for] a burnt offering; and the priest shall make an atonement for him before the LORD for his issue.
ASV
and the priest shall offer them, the one for a sin-offering, and the other for a burnt-offering; and the priest shall make atonement for him before Jehovah for his issue.