What does Exodus 12:31-42 mean?

Then he summoned Moses and Aaron by night and said, “Up, go out from among my people, both you and the people of Israel; and go, serve the LORD, as you have said. Take your flocks and your herds, as you have said, and be gone, and bless me also!” The Egyptians were urgent with the people to send them out of the land in haste. For they said, “We shall all be dead.” So the people took their dough before it was leavened, their kneading bowls being bound up in their cloaks on their shoulders. The people of Israel had also done as Moses told them, for they had asked the Egyptians for silver and gold jewelry and for clothing. And the LORD had given the people favor in the sight of the Egyptians, so that they let them have what they asked. Thus they plundered the Egyptians. And the people of Israel journeyed from Rameses to Succoth, about six hundred thousand men on foot, besides women and children. A mixed multitude also went up with them, and very much livestock, both flocks and herds. And they baked unleavened cakes of the dough that they had brought out of Egypt, for it was not leavened, because they were thrust out of Egypt and could not wait, nor had they prepared any provisions for themselves. The time that the people of Israel lived in Egypt was 430 years. At the end of 430 years, on that very day, all the hosts of the LORD went out from the land of Egypt. It was a night of watching by the LORD, to bring them out of the land of Egypt; so this same night is a night of watching kept to the LORD by all the people of Israel throughout their generations.

English Standard Version (ESV)