Acts 16:5

And so were the churches established in the faith, and increased in number daily.

The verse belongs to the account of Paul's proposed return to the churches where he had preached, to see how the believers were doing. That proposal shows his continuing care for recent converts and his desire that they remain faithful and grow strong in faith. It gives the result of Paul and his companions visiting the churches already established in Pisidia and the regions round about before pressing forward into new territory.

In going through the cities they delivered the decrees ordained by the apostles and elders at Jerusalem for the believers to keep. In this they labored in harmony with the decisions of the Jerusalem council. To be established in the faith means the churches were strengthened and made firm. Converts were helped to remain faithful and grow into strong, devoted Christians.

At the same time the churches increased in number daily. That growth was reflected in the loyalty, generosity, and brotherly love of the converts. The strengthened converts became committed to advancing God's kingdom.