[4] And they were all filled with the Holy Ghost, and they began to speak with divers tongues, according as the Holy Ghost gave them to speak. [5] Now there were dwelling at Jerusalem, Jews, devout men, out of every nation under heaven.[6] And when this was noised abroad, the multitude came together, and were confounded in mind, because that every man heard them speak in his own tongue. [7] And they were all amazed, and wondered, saying: Behold, are not all these, that speak, Galileans? [8] And how have we heard, every man our own tongue wherein we were born? [9] Parthians, and Medes, and Elamites, and inhabitants of Mesopotamia, Judea, and Cappadocia, Pontus and Asia, [10] Phrygia, and Pamphylia, Egypt, and the parts of Libya about Cyrene, and strangers of Rome,
[11] Jews also, and proselytes, Cretes, and Arabians: we have heard them speak in our own tongues the wonderful works of God. [12] And they were all astonished, and wondered, saying one to another: What meaneth this? [13] But others mocking, said: These men are full of new wine. [14] But Peter standing up with the eleven, lifted up his voice, and spoke to them: Ye men of Judea, and all you that dwell in Jerusalem, be this known to you, and with your ears receive my words.
-- Acts 2:4-14
The gift of tongues was the reversal of the confusion that arose at the Tower of Babel. The Apostles were given the gift whereby they spoke and were understood by those present.