The good news about the Lord Jesus is a reference to the good news that Jesus of Nazareth is the Christ,1 that he has died the penalty which sinners deserve for their sins, and lived the perfect life that is required to dwell in the presence of God. The fact that Jesus is proclaimed as Lord might also connect with the Greek culture in the sense that the Greeks and Romans were taught that Caesar is Lord.
20 But there were some of them, men of Cyprus and Cyrene, who on coming to Antioch spoke to the Hellenists also, preaching the Lord Jesus.