What does Revelation 17:12 mean?

The angel is explaining symbols seen by John in his vision (Revelation 17:1–6). Here, he explains the meaning of the ten horns. They are ten kings, who haven't received their kingly power, but they will receive it for a short time. Further, they will share their authority with the beast.

Based on typical interpretations of this passage, and of the timeline of the tribulation, it seems the kings will govern a confederacy of ten states at the beginning of the tribulation. Likely, this confederacy will involve nations in Western Europe, which is territory once occupied by the Roman Empire. By this interpretation, those leaders will ratify a peace treaty with Israel during their rule (1 Thessalonians 5:1–3), before trouble emerges. Perhaps the confederacy fears the rise of militant Russia, and the situation becomes too complex for the ten kings to handle, so they unite with the beast. Together, the ten kings and the beast rule, but the union endures for only a brief time. While some Bible teachers try to identify the ten kings as successive rulers in the past, this verse identifies them as kings who rule together.