John Gill Commentary Acts 2:12

"And they were all amazed, and were perplexed, saying one to another, What meaneth this?" — Acts 2:12 (ASV)

And they were all amazed
That is, all these devout men, Jews and proselytes, which came from other nations before mentioned:

and were in doubt ;
not whether the apostles spoke in various languages, nor about the sense of their words; for they not only heard them with their ears, and were assured of the facts, but they seem also to understand what was said, since they call the things delivered, the great or wonderful things of God;

but they were at a loss in their minds what should be the cause of this, or the reason of such a dispensation,

saying, one to another, what meaneth this ?
from where is it? what is the design of it? or what the end to be answered by it? or what will follow upon it? surely something considerable.