Aaron married Elisheba. She was the daughter of Amminadab and the sister of Nahshon. She had Nadab, Abihu, Eleazar and Ithamar by Aaron.
The sons of Korah were Assir, Elkanah and Abiasaph. Those were the family groups of Korah.
Eleazar, the son of Aaron, married one of the daughters of Putiel. She had Phinehas by Eleazar. Those were the leaders of the families of Levi that were recorded by their groups.
The LORD had spoken to that same Aaron and Moses. He had told them, "Bring the Israelites out of Egypt like an army on the march."
They spoke to Pharaoh, the king of Egypt, about bringing the people of Israel out of Egypt. They were that same Moses and Aaron.
The LORD had spoken to Moses in Egypt.
References for Exodus 6:28
He had told him, "I am the Lord. Tell Pharaoh, the king of Egypt, everything I tell you."
But Moses said to the Lord, "I don't speak very well. So why would Pharaoh listen to me?"