“Yahweh sold them into the hand of Jabin.” The fact that God “sold” Israel portrays them as slaves. Israel served Yahweh, who brought them out of Egypt, and so when they were not happy with Him as a “master,” He sold them to other masters, as if they might be happy with them, but of course they never were.
“Jabin king of Canaan.” This is obviously not the “Jabin” of the Book of Joshua (Josh. 11:1). “Jabin” is apparently a dynastic name. Family names were passed down generation after generation.
“Harosheth-hagoyim.” That is “Harosheth of the Gentiles.” This is likely because this was a city that Israel had not conquered and so Gentiles lived there. “Harosheth” has to do with plowing a field, so this was likely a fertile spot in the Jezreel Valley and perhaps at the foot of Mount Carmel (but the exact location is not precisely known).