Sh'mot 7:1-6 Then the L-RD (Adonai) said to Moshe, "See, I put you in the place of G-d to Pharaoh, and your brother Aharon shall be your prophet. You shall speak all that I command you, and your brother Aharon shall speak to Pharaoh that he let the sons of Israel go out of his land. But I will harden Pharaoh's heart that I may multiply My signs and My wonders in the land of Egypt. When Pharaoh will not listen to you, then I will lay My hand on Egypt, and bring out My hosts, My people the sons of Israel, from the land of Egypt by great judgments. And the Egyptians shall know that I am the L-RD, when I stretch out My hand on Egypt and bring out the sons of Israel from their midst." So Moshe and Aharon did it; as the L-RD commanded them, thus they did. And Moshe was eighty years old and Aharon eighty-three, when they spoke to Pharaoh.
I will harden Pharaoh's heart - It would be a battle between the L-rd and Pharaoh. The Egyptians considered Pharaoh a god. HaShem hardened his heart; therefore, a struggle would ensue. Already we can see HaShem is greater because He hardened Pharaoh's heart. Pharaoh did not harden G-d's heart.
How was Aharon a prophet?
The seventh letter corresponding to this chapter is Zayin-focal point of sustenance and struggle.
Sh'mot 7:8-13 Now the L-RD spoke to Moshe and Aharon, saying, "When Pharaoh speaks to you, saying, 'Work a miracle,' then you shall say to Aharon, 'Take your staff and throw it down before Pharaoh, that it may become a serpent.'" So Moshe and Aharon came to Pharaoh, and thus they did just as the L-RD had commanded; and Aharon threw his staff down before Pharaoh and his servants, and it became a serpent. Then Pharaoh also called for the wise men and the sorcerers, and they also, the magicians of Egypt, did the same with their secret arts. For each one threw down his staff and they turned into serpents. But Aharon's staff swallowed up their staffs. Yet Pharaoh's heart was hardened, and he did not listen to them, as the L-RD had said.
Pharaoh's boys got their power from HaSatan.
Ha Satan does have certain powers too, but he is limited in what he can do. Most of the time he goes around copying what HaShem does. Aharon's staff swallowed up Pharaoh's magician's staffs. Aharon uses a stake of protection against the powers of the serpent of old. This action was a long-term prophecy. The stake would be an execution stake in the future. It was a weapon against HaSatan and his path of bondage, sorrow, and death. Yeshua was victorious against Ha Satan so those who believe would not taste death. O death Where is your victory! As a short term prophecy the stake would lead the Israelites on a journey from sorrow and death to a journey toward peace and light.
Again, How is Aharon prophetic?
His actions are a prophetic picture of Yeshua.
Aharon is a type pointing to Yeshua. In the future, Yeshua would use an execution stake to protect us from our sin nature passed down through Adam when he listened to the serpent. This brought us to a staff that led us on a journey of sorrow, bondage and spiritual death. If we follow the leading of Yeshua, we now follow a staff on a journey that leads us to spiritual peace and eternal light.
Tehillim (Psalms) 23:4-6 Even though I walk through the valley of the shadow of death, I will fear no evil, for you are with me; your rod and your staff, they comfort me. You prepare a table before me in the presence of my enemies. You anoint my head with oil; my cup overflows. Surely goodness and love will follow me all the days of my life, and I will dwell in the house of the L-RD forever. NIV
Those who continue on the path of the serpent and the world will only become an enemy of HaShem. This too would eventually lead them to be swallowed up into darkness just like the snake.
James 1:4 And let endurance have its perfect result, that you may be perfect and complete, lacking in nothing.
Jude 1:11-14 Woe to them! For they have gone the way of Cain, and for pay they have rushed headlong into the error of Balaam, and perished in the rebellion of Korah. These men are those who are hidden reefs in your love feasts when they feast with you without fear, caring for themselves; clouds without water, carried along by winds; autumn trees without fruit, doubly dead, uprooted; wild waves of the sea, casting up their own shame like foam; wandering stars, for whom the black darkness has been reserved forever. NAS