Exodus chapter 7 is the beginning of the plagues that God sends upon Egypt in order to convince Pharaoh to let the Israelites go. In this chapter, God instructs Moses to go to Pharaoh and demand that he let the Israelites go. God also tells Moses that he will harden Pharaoh's heart so that he will not listen. God then tells Moses to tell Aaron to throw down his staff and it will turn into a serpent. This is a sign to Pharaoh that God is with Moses and Aaron.
The chapter ends with Pharaoh's magicians being able to replicate the miracle, but Aaron's staff swallows up their staffs. This is a sign to Pharaoh that God is with Moses and Aaron and that Pharaoh should let the Israelites go.
This chapter is important because it sets the stage for the plagues that will follow. It also shows the power of God and how He is able to work through Moses and Aaron to accomplish His will. It is a reminder to us that God is in control and that He will always be with us, even when it seems like all hope is lost.