What does Genesis 47:17 mean?
The land of Egypt and nearby Canaan is barren. It has been barren for several years, and the famine will last for several more. Earlier verses described the land using terms related to fainting and insanity (Genesis 47:13). Joseph, as Pharaoh's representative in Egypt, holds great stores of grain. These were built up through taxes (Genesis 41:33–36), then sold back to the people for cash (Genesis 41:55–57).Just two years into the seven-year disaster (Genesis 45:6), the people of the region have no more money to buy grain. They are still in danger of starvation. Joseph has suggested an alternative: trade livestock for food. It's not clear whether Joseph meant to literally hand over animals, physically, or simply consign their ownership to Pharaoh. This might have been a kind of mortgage or other arrangement.
Regardless of such details, the people comply. They don't have much choice since the alternative is starvation. So, the Egyptians and the Canaanites bring their horses, sheep, cows, and donkeys to Joseph. In whatever sense Joseph arranged, the ruler of Egypt now owned almost all the herded animals in Egypt and the surrounding region.