by the power of signs and wonders, by the power of the Spirit of God—so that from Jerusalem and all the way around to Illyricum I have fulfilled the ministry of the gospel of Christ; (ESV)
God had used the Apostle Paul to do amazing works in bringing the Gentiles to faith and obedience in Jesus Christ. How was Paul able to be authenticated in delivering his message to people all over the world? By the power of signs and wonders, by the power of the Spirit of God. God spoke through apostles and prophets then. Now we have the completed canon of Scripture which is our authority.
Paul describes how the Gospel has been brought from Jerusalem all the way to Illyricum. As is usually the case, we read such a location and have no idea where the Scripture is referring. The area of Illyricum is the area of former Yugoslavia and current Northern Albania. From Jerusalem to Illyricum is an area spanning approximately 1400 miles.
Before there was such a thing as automobiles the Gospel had been brought from Jerusalem, where the church began, all the way to Illyricum, which would certainly have been considered the "ends of the Earth" at that time. The Roman roads would have been a help in people bringing the Gospel, but it still would have required people to walk great distances.
In Acts 1:8 Jesus told the disciples that they would be his disciples in Jerusalem, Judea, Samaria, and to the ends of the Earth. The Apostle is celebrating the fact that the power of the Holy Spirit has enabled him, and many others, to bring the Gospel from Jerusalem to the very ends of the Earth. God was faithful, and so was the Apostle Paul.
What area is God calling you to be a minister of the Gospel? Have you asked the Holy Spirit to help you and empower you in this task?