The document discusses the biblical gift of speaking in tongues. It describes tongues as a spiritual gift given by the Holy Spirit that allows believers to speak in other languages. The three main types of tongues mentioned are evidential tongues as evidence of being filled with the Holy Spirit, a gift of tongues for prophecy or message in the church that requires interpretation, and an unknown "prayer language" for personal edification and intercession. The document provides several biblical references from Acts and 1 Corinthians to support these manifestations of tongues and their purpose to strengthen believers and the church.