The laying on of hands is a special gesture: the hands of the apostles, which represent the hands of their Lord Jesus. It is specifically a gesture that underscores the prayer: Dispense your Spirit via our hands in a manner that we can feel and see, so that the believers may receive the Spirit as gift upon our prayers.
In Acts we see the laying on of hands more often with the prayer to receive the gift of the Spirit (compare Acts 6:6; Acts 9:12, Acts 9:17; Acts 13:3; Acts 19:6).
17 Then they laid their hands on them and they received the Holy Spirit.