Rev 12:3

3 Another sign was seen in heaven. Behold, a great red dragon, having seven heads and ten horns, and on his heads seven crowns.

a great red dragon – the four beasts of Daniel were described as four Kings (Dan 7:17) and four kingdoms (Dan 7:23). From Daniel 8, we know that the fourth King is Satan, the little horn that became “exceedingly great.” He is King of the Latins, who were called “the people of the ruler to come” (Dan 9:26).

of seven heads and ten horns – the dragon of seven heads and ten horns represents the fourth beast as a King; and the beast of seven heads and ten horns in Rev 13 and Rev 17 represents the fourth beast of Daniel as a “kingdom” which is identitied by the number 666, the name of the name “Latienos” in Rev 13:18. The identity of the seven heads is described in Rev 17:9-10. These are the seven kingdoms that held the saints in captivity: Egypt, Assyria, Babylon, Persia, Greece, Rome, and the Ten Kings of Europe which are called “a kingdom.”

on his heads seven crowns – the position of the crowns will signifiy the time period. In Rev 13:2, the crown move to the ten horns signifying the relationship of the bishop of Rome with the ten states of Europe that came out of the Roman Empire.