In the book of Genesis we read about Joseph. He was one of the 12 sons of Jacob. God gave Jacob another name, Israel. Joseph's brothers sold him as a slave, to work in Egypt. Later, there was a famine and all of Jacob's family went to live in Egypt. Joseph forgave his brothers for what they had done to him.
Exodus continues the story of Jacob's family in Egypt. It tells us these things:
How God brought Jacob's descendants, the Israelites, out of Egypt.
How God led them through the wilderness.
How God gave his Laws to Moses for the Israelites.
How the Israelites built the tabernacle and how they worshipped God in it.