Here they are filled with the Holy Spirit and began to speak other languages that they did not know how to speak before. An example would be some one that could only speak English now with the Holy Spirit could also speak Japanese. And there were dwelling at Jerusalem Jews, devout men, out of every nation under heaven. There were Jews from around the world that feared God living in Jerusalem at this time. V6 Now when this was noised abroad, the multitude came together, and were confounded, because that every man heard them speak in his own language.
Language means dialect.
They were confounded because they understand what these men were saying in their own language, right down to the very dialect from where they were born. This is what the true gift of tongues is all about. When someone has the true gift of tongues from the Holy Spirit it does not matter where that person is from or that he or she could not have spoken your language before it happened. You will be able to understand everything they say right down to your very dialect from where you were born. The ones with the gift of tongues were from Galilee.