The Lord Jesus breathed on His disciples and said, “Receive the Holy Spirit. If you forgive anyone his sins, they are forgiven; if you do not forgive them, they are not forgiven.” (Jn 20:22–23)
Jesus gives his ministers the authority to forgive sins (Jn 20:22–23)
The pastor speaks by Christ’s command to forgive and retain sins (Jn 20:22–23)
All Christians forgive one another and remind each other of the forgiveness which is ours in Christ Jesus (Mt 6:12, Mt 7:1–5, Mt 18:21–35; Eph 4:32)
If you want more information on Confession and its meaning,
check out the Small Catechism.