Acts 13:5

And when they were at Salamis Salamis was the nearest port of Cyprus for voyagers from Seleucia. It is at the eastern end of the island in the bay which is now called Famagousta.

in the synagogues of the Jews who were living in Salamis in sufficient numbers to need several synagogues.

they had also John to[as] their minister This is John Mark, the nephew of Barnabas. His office may have been to baptize, from which service the Apostles seem to have refrained where it was possible (see above on Acts 10:48). But there is perhaps also implied in the word rendered "minister" some degree of the same service which in old times Elisha rendered to Elijah (2 Kings 3:11). The same Greek word is used for the minister in a synagogue (Luke 4:20).