And when they cried to YHVH, he put darkness between you and the Egyptians and made the sea come upon them and cover them; and your eyes saw what I did in Egypt. And you lived in the wilderness a long time.
Joshua 24:7

Smoke or thick clouds is a frequent manifestation of the presence of God. The pillar of smoke and fire was God whose presence separates His people from all the nations of the world. God hid Israel from Egypt, hid Egypt beneath the sea, then revealed himself to Israel. It's impossible for the world/Egypt to fully comprehend the Kingdom/Israel. A pillar of darkness lies between us.