Derek Prince discusses the vocal gifts of the Holy Spirit, specifically focusing on tongues, interpretation, and prophecy. He emphasizes that these gifts are supernatural and must be controlled by the believer, unlike the gifts of revelation and power which are solely initiated by God. Prince explains the significance of speaking in tongues as a vital aspect of the baptism in the Holy Spirit, asserting that it is an essential evidence of this experience. He also highlights the importance of understanding the proper use and purpose of these vocal gifts to avoid misuse and confusion within the church. Ultimately, he encourages believers to yield their tongues to the Holy Spirit for effective ministry.