Luke recorded that Paul added two new bits of information that he had not mentioned in his previous testimonies ( Acts 26:14). On the Damascus road all of his companions had fallen to the ground as a result of the bright light. This shows that the event was real and not a vision that Paul had. Also, the Lord had spoken to him in Aramaic, probably to confirm to Paul that the One addressing him was the God of the Jews. [source][source][source]
Goads were sharp sticks used to drive cattle. The figure of kicking against goads was and is a common rural metaphor that describes opposing the inevitable (like "banging your head against a wall"). Such action only hurts the one doing it, not the object of his hostility. This was the case in Paul"s antagonism to God that his persecution of Christians expressed. [source][source][source]
"In the Greek world this was a well-known expression for opposition to deity (cf. Euripides Bacchanals 794-95; Aeschylus Prometheus Bound 324-25; Agamemnon 1624; Pindar Pythia 294-95; Terence Phormio 1227). Paul may have picked it up in Tarsus or during his missionary journeys. He used it here to show his Greek-oriented audience the implications of the question "Saul, Saul, why do you persecute me?" Lest he be misunderstood as proclaiming only a Galilean prophet he had formerly opposed, he pointed out to his hearers what was obvious to any Jew: correction by a voice from heaven meant opposition to God himself. So he used a current expression familiar to Agrippa and the others ..." [1][source]
Paul related his conversion experience on this occasion very graphically, and he stressed the significance of these events. [source][source][source]