In Genesis, we find that God told Abraham that his family would live in Egypt for 400 years. “You can be sure that your descendants will be strangers in a foreign land, where they will be oppressed as slaves for 400 years.” Gen. 15.13 (NLT). Exodus is about how that ended.
Exodus can be outlined as:
1A. The birth and training of a leader. Chapters 1-2
2A. The overcoming of slavery. Chapters 3-14
3A. The establishing of a covenant. Chapters 15-40
The key verse is Exodus 20:19: “And they said to Moses, ‘You speak to us, and we will listen. But don’t let God speak directly to us, or we will die’!” (NLT). The reason this is key is because in Chapter 19 God offered to make them “My kingdom of priests, My holy nation”. God wanted a relationship with the individual, but the people backed away from that so God created a priestly lineage from the tribe of Levi.