The Book of Exodus is a story in the Bible that talks about how the Israelites, who were the people who believed in God, were slaves in Egypt. They had been slaves for a long time and had to work really hard every day. But then God chose Moses to help the Israelites escape from Egypt and go to a new land that God promised them.
Moses talked to the Pharaoh, who was the leader of Egypt, and asked him to let the Israelites go free. But the Pharaoh didn't want to let them go, so God sent ten plagues to convince him to change his mind. Some of these plagues included turning the water into blood and sending a swarm of frogs all over Egypt.
Finally, the Pharaoh agreed to let the Israelites leave Egypt, and they started on their journey to the new land. But then the Pharaoh changed his mind again and chased after them with his army. God helped the Israelites by parting the Red Sea so they could cross safely, but then closed it back up so the Pharaoh's army couldn't follow them.
The Israelites eventually made it to the new land that God promised them, but it wasn't an easy journey. They had to overcome many challenges, and God gave them rules to follow to help them stay on the right path. Overall, the Book of Exodus tells the story of the Israelites' journey from slavery in Egypt to a new life in a promised land, and how God helped them along the way.