Although almost all translations say that Paul spoke to them in Hebrew, actually Paul would have been speaking in Aramaic, the language which the Jews of that day used (see New English Bible “in the Jewish language”). Spoke to them in Hebrew may be rendered as “spoke to them; the words he used were Hebrew words,” “spoke to them, using the Hebrew language,” “spoke to them in their own Jewish language,” or “… in the language used by the Jews.”

Quoted with permission from Newman, Barclay M. and Nida, Eugene A. A Handbook on The Acts of the Apostles. (UBS Handbook Series). New York: UBS, 1972. For this and other handbooks for translators see here .