Translation
Then all of them were completely filled up by the Holy Spirit and began to utter sounds
Go to footnote numberin other tongues
Go to footnote numberas the Spirit was giving dignified speech
Go to footnote numberto them.
Paraphrase
Then all of the followers of Jesus that were present were filled with a complete supply of the Holy Spirit of God and they began to utter God-given sounds that were mysterious, and yet the Holy Spirit also made those sounds clear, meaningful, and special.
Footnotes
1: "sounds"
This is one of the Greek words meaning “to talk or speak” but its emphasis is different from the other major word that is used in John 1:1 and is related to speaking words with clear meaning. By contrast, this word was used in classical Greek of “idle prattle” and in the New Testament of “uttering sounds” many of which were unintelligible, including sounds made by animals and inanimate objects. The choice of this word is purposefully intended to communicate the utterance of sounds that were not clearly understood (I will explain this further in a moment).
2
This word means “tongues/languages.” See the comment after this verse for an introduction to the topic of tongues.
3
This word means “to speak forth or declare something clearly, to speak forth with dignified, elevated discourse.” It was the type of speaking one would expect from a prophet, a philosopher, or a sage. It stands in stark contrast to the word used earlier in this sentence which pointed to unintelligible sounds.
BOTH UNINTELLIGIBLE SOUNDS AND DIGNIFIED SPEECH AT THE SAME TIME
Notice that, according to Acts 2:4, their speaking came forth both as unintelligible sound and dignified speech at the same time. It was unintelligible to the Jews, but it made sense to some people and for them it carried an important message. Thus, it was dignified speech to those that understood it.
In this event God was bridging the gap created between the nations at the tower of Babel due to man’s arrogance and disobedience.