John Gill Commentary Acts 11:24

"for he was a good man, and full of the Holy Spirit and of faith: and much people was added unto the Lord." — Acts 11:24 (ASV)

For he was a good man
He had the grace of God wrought in his soul, and did good works; he was very kind, and generous, and charitable; he sold what land he had, and gave the money to the apostles, for the use of the community, (Acts 4:37)

and full of the Holy Ghost, and of faith ;
he was full of the several graces of the Spirit, and particularly of faith; and he was full of the extraordinary gifts of the Spirit, and of the faith of miracles; he was full of the doctrine of faith, and of spiritual gifts for the preaching of it: the same character is given of Stephen, (Acts 6:5)

and much people was added unto the Lord ;
by the means of Barnabas, through his ministry, and the exercise of those gifts he was full of; so the Arabic version, "and he drew a large multitude to the Lord".