To hie is to move in a hurried or hasty way. It's the kind of word you are more likely hear in a Shakespeare play, like when a character demands, "Hie thee hither!"
The verb hie is extremely old fashioned, so you're much more likely to read it in a book than to hear someone say it. Still, it's good to know when you read, "Hie thee to the castle!" that it means "Hey, get a move on! Go to the castle!" It comes from the Old English word higian, "strive or hasten," from a Proto-Germanic root.