God's hand signifies his powerful help. Alternate translation: "God was powerfully enabling those believers to preach effectively" (See: [[rc://en/ta/man/jit/figs-metonymy]])
Here "turned to the Lord" is a metaphor for starting to obey the Lord. Alternate translation: "they repented of their sins and began to obey the Lord" (See: [[rc://en/ta/man/jit/figs-metaphor]])