“Los que se acercan al sacramento de la penitencia obtienen el perdón misericordioso de Dios por la ofensa cometida contra él, y son, al mismo tiempo, reconciliados con la Iglesia la cual han ofendido con sus pecados y la cual con caridad, con ejemplo, y con su oración labora para nuestra conversión (CCC 1422).

The Sacrament of Reconciliation is one of the most unique and beautiful aspects of Catholicism. Jesus Christ, in His abundant love and mercy, established the Sacrament of Confession, so that we as sinners can obtain forgiveness for our sins and reconcile with God and the Church. The sacrament “washes us clean,” and renews us in Christ.
“Jesus said to them again, ‘Peace be with you. As the Father has sent me, even so I send you.’ And 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; if you retain the sins of any, they are retained’” (John 20:21-23).

http://www.catholicscomehome.org/your-questions/what-is-the-sacrament-of-confession/