Acts 2:11 – we hear them speaking in our own tongues the wonderful works of God.
Acts 10:44-46 – While Peter was still speaking these words, the Holy Spirit fell upon all those who were listening to the message. All the Jewish believers who came with Peter were amazed, because the gift of the Holy Spirit had also been poured out on the Gentiles. For they were hearing them speaking with tongues and exalting God.
These verses describe the basic ingredient of the prayer language seen for the first time in Acts 2; this ingredient is worshipping and magnifying God. If you really think about it nothing else would make better sense. When someone is touched powerfully by the power of the Spirit they become suddenly aware of the goodness and greatness of God. The response is always the same, we fall in love with Him and have a strange and strong desire to worship Him. Our hearts are awakened and we just can’t find words big enough or expressive enough to describe and worship Him the way He should be worshipped. That brings us to the very center of this experience called the Baptism in the Holy Spirit, we worship Him from our hearts with supernatural words given to us to adequately describe Who He is. As for this experience for Peter and his fellow companions in Acts 10, this supernatural worship by the gentiles was what convinced them of the legitimacy of their conversion experience. Here is how the Tyndale Commentary describes this.
“Whether or not Peter was surprised by what happened, they (Peter’s Jewish companions) certainly were. It was one thing to make an attempt to preach to Gentiles; it was quite another to see the sermon interrupted by the clear signs of their conversion and reception of God’s gift. There could be no mistake about what had happened. Just as the first Jewish believers had received the Spirit and praised God in other tongues on the day of Pentecost, so now these Gentiles received the identical gift of God.”
This prayer and worship language is greatly misunderstood by many believers. Apparently many get confused by the restrictions Paul placed on the prophetic gift of tongues which was intended to be a message from the Lord in tongues which needed to be interpreted. There is no need to interpret our worship and adoration of God, when you hear it you know exactly what it is.