Thanks for your question. I would like to respond directly from Christ Our Pascha Catechism of the Ukrainian Catholic Church:

450. In the celebration of the Holy Mystery of Repentance, the Church actualizes the words of the Lord to the apostles: “Receive the Holy Spirit. If you forgive the sins of any, they are forgiven them; if you retain the sins of any, they are retained” (Jn 20:22-23). Every priest continues the apostolic ministry in the Mystery of Repentance when he absolves the faithful of their sins and reconciles them with the Church. The priest pronounces the prayer of absolution (the loosing from the bondage of sin) and every penitent thereby receives Christ’s forgiveness.

A priest’s authority to convey forgiveness does not come from himself. It comes from Christ. By the power of the Holy Spirit, the priest stands as a witness to Christ’s love and mercy in declaring the sinner forgiven.

Three basic Scripture passages underlie the practice of Confession:

1. Matt 16:18-19 “And I tell you, you are Peter, and on this rock, I will build my church, and the gates of Hades will not prevail against it. I will give you the keys of the kingdom of heaven, and whatever you bind on earth will be bound in heaven, and whatever you loose on earth will be loosed in heaven.”
2. Matt 18:18 “Truly I tell you, whatever you bind on earth will be bound in heaven, and whatever you loose on earth will be loosed in heaven.”
3. John 20:21-22: Jesus said to them again, “Peace be with you. As the Father has sent me, so I send you.” When he had said this, he breathed on them and said to them, “Receive the Holy Spirit. If you forgive the sins of any, they are forgiven them; if you retain the sins of any, they are retained.”