What does Exodus 3:3 mean?

Moses is tending his father-in-law's sheep (Exodus 3:1), having settled in Midian (Exodus 2:16–22) after fleeing his birth home of Egypt (Exodus 2:14–15). One day, Moses noticed a bush which was burning with fire, but not "burnt up" by the fire. Here, Moses says he will investigate. Moses may have only thought these words to himself, though it is possible he spoke the words aloud. He calls it a "great sight," meaning he clearly understood something unique was taking place. Moses was certainly familiar with fire and knew that fire is supposed to destroy wood. He wanted to know why this situation was different.

God is often associated with fire (Genesis 15:17; 19:24; Exodus 24:17; 40:34–38; Deuteronomy 4:24; 9:3; Psalm 50:3; Isaiah 30:23–32; 33:14–16; 66:15–16; Daniel 7:9–10; Acts 2:1–4; Hebrews 12:28–29). After freeing them from Egypt, God will appear before the Israelites in the form of a pillar of fire (Exodus 13:17–22). He would lead His people to return to this very mountain where Moses would experience the Lord once again and receive the Ten Commandments directly from the Lord (Exodus 19—20). The Lord remained as a fire to give the people light for travel, revealing His power as He led His people from Egyptian slavery (Exodus 13:21–22).