What does Exodus 1:4 mean?

Exodus opens by explaining Israel's initial settlement in Egypt. Four more of Jacob's sons are mentioned in this verse. Dan was the child of Jacob and Rachel's servant Bilhah. When Rachel was barren, she told Jacob to have a child with her servant so Rachel would have a child accounted as her own (Genesis 30:1–6). Jacob and Bilhah also had a second son named Naphtali, making Dan and Naphtali brothers with the same father and mother (Genesis 30:7–8).

Leah stopped bearing children for a time and she also gave Jacob her servant, named Zilpah, "as a wife" (Genesis 30:9). Jacob and Zilpah had two sons together named Gad and Asher, whose names mean "good fortune" and "happy" (Genesis 30:9–13). In their culture, sons born through a wife's servant were considered children of the servant's owner. Gad and Asher were both born in Paddan-aram (Genesis 35:26).