catholic.com/qa/is-the-priest-another-christ-when-he-says-holy-mass-hears-confessions-etc
Full Question
Is the priest “another Christ” when he says Holy Mass, hears confessions, etc.?
Answer
The Church teaches that the priest ministers in persona Christi, in the person of Christ. In speaking to his disciples, Jesus said, “He who hears you hears me, and he who rejects you rejects me” (Lk 10:16). “Receive the Holy Spirit. If you forgive the sins of any, they are forgiven; if you retain the sins of any, they are retained” (Jn 20:22–23).
cfpeople.org/SeminarianWritings/Sem033.html
Thus, Christ bestows the effects of his priesthood and his priestly action on the Church by allowing other men to participate in his one priesthood. Just as Christ redeemed us by a priestly act of worship, so the ordained priest, by virtue of his participation in Christ’s priesthood, offers that same sacrificial act of worship on the altar. “The sacrifice which is offered every day in the Church is not distinct from that which Christ Himself offered, but is a commemoration thereof.” The priest, who is a sharer in the priesthood of Christ, offers the Mass in the Person of Christ.