# Who is Abimelek, and who is Shechem, that we should serve him?

"We should not serve Abimelek, that is, Shechem!" 

# Is he not the son of Jerub-Baal? Is Zebul not his overseer?

"He is just the son of Jerub-Baal, and Zebul is just his overseer." 

# overseer

Zebul oversaw Abimelek's slaves, servants, and laborers.

# Zebul

This is the name of a man.

# Serve the men of Hamor, Shechem's father

Gaal means the people of Shechem should serve those who descended from Hamor; that is, those who are truly Canaanites, and not serve someone whose father was an Israelite.