Read this week's lectionary readings here.
35 Then Philip opened his mouth, and beginning from this Scripture he preached Jesus to him.
36 and the eunuch said, "See, here is water! What prevents me from being baptized?"
Philip must've explained how Jesus was the one promised in that Scripture, the prophecy of Isaiah. He must've explained the Good News that Jesus was the one who had stood on trial for the sins of the world, been found guilty and executed, been raised to life as the Scriptures had promised, and who now offered salvation to all who called on His name. He must've explained that anyone who accepted Jesus would be saved from sin and death, and how to accept Jesus, and the eunuch was thinking about it, and wanted that. And then the opportunity presented itself, and the eunuch called.
And the Lord answered.
Praise His name.