The Catechism in Questions & Answers

415. What do we mean by “authorisation” for a spiritual ministry?

A spiritual ministry is conferred by an Apostle by the commission of Jesus Christ. Thereby the recipient of the ministry receives part of the authority of the Apostle. He is to make use of this authority by commission of the Apostle. The recipient of this ministry thereby acts in the name of the Apostle and represents him in the scope defined for that ministry. After all, the Apostle is the one who sends the ministers, and those who are sent are accountable to, and dependent on, their sender.

Examples of activities performed by authorisation:
When the Apostle proclaims the forgiveness of sins, he is acting on the basis of the authority conferred upon him by Jesus Christ (concerning this see Question 424). It is for this reason that the Apostle proclaims the forgiveness of sins with the words: “I proclaim  unto you the glad tidings: in the name of our Lord Jesus Christ, the Son of theliving God, your sins are forgiven.”
When the priestly minister proclaims the forgiveness of sins, he acts in the stead of the Apostle. For this reason the priestly ministry proclaims the forgiveness of sins with the words: “In the commission of my sender, the Apostle, I proclaim unto you the glad tidings: in the name of our Lord Jesus Christ, the Son of the living God, your sins are forgiven.”