The term Hebrews
is an ethnic term. It first occurs in Genesis 14:13 as a description of Abram.1 It possibly came to be used to refer to people who descended from Eber, the great-grandson of Shem (Genesis 10:21–25; Genesis 11:10–17).2 For the Hebrews to be slaves (NIV: subject) to the Philistines means that they either paid some kind of tribute or were forced to work as servants. It was primarily men from the tribe of Judah who were subject to the Philistines, seeing as their tribal allotment was right next to the territory of the Philistines (see Judges 15:9–11).
9 Take courage, and be men, O Philistines, lest you become slaves to the Hebrews as they have been to you; be men and fight.”