Dan 7:24

24 As for the ten horns, out of this kingdom shall ten kings arise: and another shall arise after them; and he shall be diverse from the former, and he shall put down three kings. 

the ten horns are ten kings – they are also kingdoms, the Ten European states. Some have imagined them as ten kings who shall arise from the Roman Empire, and tried to count ten Emperors. However, the true understanding of these as ten kingdoms explains how the beast continued, even though one of its heads was crushed (Rev 13:3), ie, the fall of the Roman Empire.

another will arise after them – the working of the Antichrist, the little horn, most certainly preceded the ten states of Europe. But the Bishop of Rome, in the “political” realm did not become a political force among the states of Europe until after the European states were established. One of the most visible evidences of his power was seen in A.D. 800, when the Pope crowed the Frankish King Charlemagne as Emperor of the Holy Roman Empire.

he shall be different from the first ones – he is not the king of a state.

shall subdue three kings – which are the three Latin states of Spain, France and Italy. The beast is described by the number 666, meaning “Lateinos.” See explanation under Dan 7:8.