[Jesus, speaking to His disciples on Easter Sunday night]: And when He had said this, He breathed on them, and said to them, "Receive the Holy Ghost. Whose sins you shall forgive, they are forgiven them; and whose sins you shall retain, they are retained."
The Church has always understood--and has in fact defined--that Jesus Christ here conferred on the Apostles authority to forgive sins, a power which is exercised in the Sacrament of Penance. "The Lord then especially instituted the Sacrament of Penance when, after being risen from the dead, He breathed upon His disciples and said: "Receive the Holy Spirit...' The consensus of all the Fathers has always acknowledged that by this action so sublime and words so clear the power of forgiving and retaining sins was given to the Apostles and their lawful successors for reconciling the faithful who have fallen after Baptism" (Council of Trent, "De Paenitentia", Chapter 1).
The Sacrament of Penance is the most sublime __expression of God's love and mercy towards men, described so vividly in Jesus' parable of the prodigal son (cf. Luke 15:11-32). The Lord always awaits us, with His arms wide open, waiting for us to repent--and then He will forgive us and restore us to the dignity of being His sons.
The Popes have consistently recommended Christians to have regular recourse to this Sacrament: "For a constant and speedy advancement in the path of virtue we highly recommend the pious practice of frequent Confession, introduced by the Church under the guidance of the Holy Spirit; for by this means we grow in a true knowledge of ourselves and in Christian humility, bad habits are uprooted, spiritual negligence and apathy are prevented, the conscience is purified and the will strengthened, salutary spiritual direction is obtained, and grace is increased by the efficacy of the Sacrament itself" ([Pope] Pius XII, "Mystici Corporis").
Source: "The Navarre Bible: Text and Commentaries"