Ego te absolvo a peccatis tuis in nomine Patris et Filii et Spiritus Sancti, Latin for I absolve you from your sins in the name of the Father and of the Son and of the Holy Spirit.
In Catholic theology there are three main conditions for any sacrament to be valid:
- The person performing the sacramental ritual must be capax, that is to say capable of performing the sacrament. In the case of the sacrament of reconciliation (popularly known as confession), the person must be a validly ordained priest, and he must have the jurisdiction (historically, priests were limited to a specific territory in which they could give a valid absolution).
- That person must have the intention of performing a sacrament. So, for example, if an ordained priest with proper jurisdiction were acting in theatre saying the above words intending to act rather than absolve, he would not be performing the sacrament of reconciliation.
- Last but not least, the person performing the sacrament must say the words specifically designated by the Church for that sacrament. These words are so specific so that if a priest started saying a mass, for example, and died of a massive heart attack during the mass, it is easy to determine whether everyone there attended a mass or not based on whether the priest got to saying the words of consecration or not.
The above words are the exact words the priest must say to give one an absolution. He may say them in Latin, or English, or any other language (as long as they are the exact words approved by the bishops' conference for that language as the proper translation of the Latin formula).
As with all sacramental rituals, the priest normally says more than those words. However, every priest knows those are the exact words that actually make the confession into a sacrament.
In the specific case of the sacrament of reconciliation, the absolution can only be valid if the person being absolved is sorry for his sins. So, in an emergency when someone is about to die in any second, a priest may dispense with everything else in the ritual and just ask the person whether he is sorry for his sins (or even just ask him to be sorry), and then say the above words.
It may be interesting to point out that the priest does not say "I forgive you your sins," but "I absolve you from your sins." This is because according to Catholic beliefs, only God can forgive sins, a priest can only perform a sacrament which results in God's forgiveness. One might argue that the difference is mere semantics, but I am simply trying to describe the specific beliefs of the Catholic Church and the practice that is a direct result of those beliefs. And to them the disctinction is very clear: The priest absolves, God forgives.