What does Acts 7:35 mean?
Moses was a Hebrew man who had been raised by an Egyptian princess (Exodus 2:1–10). Somehow, in a way that the original account does not explain, he knew God had sent him to free his people from slavery (Acts 7:25). During his first attempt, Moses killed an Egyptian who was beating a Hebrew. The next day, he realized the Israelites not only rejected his help and authority, they knew about the murder. Moses fled to Midian before Pharaoh could execute him (Exodus 2:11–15).In Midian, Moses married the daughter of a priest and cared for his father-in-law's sheep. Forty years after his arrival, he realized a bush was on fire but not burning. The angel of the Lord was in the bush, and God spoke to Moses. Moses' authority came from that angel's "hand," that is, by the angel's authority.
The original passage says "the angel of the LORD" was in the flaming bush (Exodus 3:2). Stephen just says, "an angel" (Acts 7:30). It's thought that when the Old Testament refers to "the angel of the LORD," it means the pre-incarnate Christ. It would be helpful if Stephen would clarify that, here, but he doesn't.
Before Moses fled to Midian, an Israelite man asked him, "Who made you a prince and a judge over us?" (Exodus 2:14). "Prince" refers to an official or a representative of the king (Pharaoh). A "judge" is someone authorized to make a legal ruling. Stephen points out that Moses was, indeed, an official ruler, a representative of God. More than that, God chose him to be the Israelites' redeemer, to rescue them. The arguing Israelites derisively rejected Moses' position as a judicial representative of Pharaoh, not realizing Moses was sent by God to rescue them.