What is the meaning of Acts 15:12?

12 Then all the multitude kept silence, and gave audience to Barnabas and Paul, declaring what miracles and wonders God had wrought among the Gentiles by them. (Acts 15:12 KJV)

William Burkitt’s Commentary

The second speech made in this council, was that of Barnabas and Paul, who declared what miracles God had enabled them to work among the Gentiles, which was an evidence of God’s approbation of the Gentiles, though uncircumcised, and that he was pleased with their adminstration among them.

Hence they conclude very well, that the miracles wrought among the Gentiles, and the Holy Ghost descending upon the Gentiles, was God’s approving testimony, in the case that the believing Gentiles, without circumcision, should find no less acceptance with God than the believing Jews, who were of the circumcision.