What can we infer Philip told the Ethiopian eunuch from his request to be baptized?

The eunuch's request implies Philip had told him that Isaiah 53 spoke of Jesus, who walked in Palestine, was put to death and raised from the dead. God was still ready to make Him King of Israel, and Israel needed to repent, especially of the sin of crucifixion.

Les explains that the New Testament wasn't written yet, so Philip could only use the Old Testament. He began at the same scripture—Isaiah 53—and preached unto him Jesus. Although the text does not explicitly say Philip preached Jesus crucified and resurrected, the eunuch's request to be baptized reveals what Philip had been telling him: that Isaiah 53 was speaking of Jesus, who had walked three years in Palestine, had been put to death, had been raised from the dead, and God was still ready to let him be the King of Israel. Israel's responsibility under the law was to repent especially of the sin of crucifixion.

What had Philip been telling the Ethiopian eunuch right before he asked to be baptized?

Philip had been telling him that if he believed Isaiah 53 spoke of Jesus—who walked three years in Palestine, was put to death, raised from the dead, and was still ready to be Israel’s King—and that Israel was to repent especially of the sin of crucifixion. This prompted the eunuch’s baptism request.