What does Genesis 46:19 mean?

This is part of a segment detailing all Jacob's sons and grandsons living at the moment the family entered Egypt (Genesis 45:9–1; 46:1–4). Previous verses listed Jacob's descendants by his wife Leah and servant-wife Zilpah. Now the two sons of Jacob's beloved wife Rachel are listed, Joseph and Benjamin.

After many years of barrenness, Joseph was finally born to Rachel outside of the land of Canaan (Genesis 30:24). His name is literally a prayer for another son. That son Benjamin was finally born as Rachel died in the land of Canaan (Genesis 35:18). From that time on, Joseph and Benjamin became Jacob's favorite sons, leading to much resentment from the sons borne by his other wives.