"'Then I asked, "Who are you, Lord?" "I am Jesus, whom you are persecuting," the Lord replied.'" NIV translation
We see, here, that he was acting out of ignorance because he did not really know who Jesus was. We also see the fact that God considers persecution of His children to be persecution of Him. You can almost feel Paul's compassion as he trys to make those gathered see that they are in the same position that he had been in. This is a good example for us of how we are to have compassion and understanding towards those who are against us.
"'Now get up and stand on your feet. I have appeared to you to appoint you as a servant and as a witness of what you have seen of me and what I will show you.'" NIV translation
Jesus told Paul to stand up and commissioned him as an apostle. Although there are many today that claim the title of apostle, we cannot rightly do so.
An apostle was taught by Jesus in person and then sent out to teach others. We see both of these conditions met in this verse as Paul describes what happened.
"'I will rescue you from your own people and from the Gentiles. I am sending you to them to open their eyes and turn them from darkness to light, and from the power of Satan to God, so that they may receive forgiveness of sins and a place among those who are sanctified by faith in me.'" NIV translation
Jesus continues to commission Paul as an apostle and promises to rescue him from the trials that are to come. We all have probably felt, at some point in time, that the whole world is against us. Here, Paul is told that the whole world (both Jews and non-Jews) will be against him. He is told his mission and the purpose for it. We, like Paul, can hold onto this promise that Jesus will rescue us from all of the trials that we face no matter what the odds.
"'So then, King Agrippa, I was not disobedient to the vision from heaven. First to those in Damascus, then to those in Jerusalem and in all Judea, and to the Gentiles also, I preached that they should repent and turn to God and prove their repentance by their deeds.'" NIV translation
People had been trying to portray Paul as a lawless rebel but, here, he lets the king know that he was, in fact, telling the people to repent and turn back to the ways of God. This passage describes the age old struggle between salvation by grace and works. There are those who want to put them in the wrong order even today. What Paul is saying here is that we are saved by grace and because we are saved our actions are different. This difference in our actions is proof of our repentance and salvation but the actions themselves cannot repair our broken relationship with God. That only comes through the blood of His Son Jesus Christ.