“And the beast which I saw was like unto a leopard, and his feet were as the feet of a bear, and his mouth as the mouth of a lion: and the dragon gave him his power, and his seat, and great authority.” (Rev 13:2 KJV)
The beast is symbolic of the antichrist and the kingdoms he rules. The antichrist gets his position from Satan who rules the kingdoms. The beast and the kingdoms were prophesied by Daniel.
Out of the Sea
“And I stood upon the sand of the sea, and saw a beast rise up out of the sea, having seven heads and ten horns, and upon his horns ten crowns, and upon his heads the name of blasphemy.” (Rev 13:1 KJV)
The sea represents the world nations. The beast rising out of the sea is a compilation of the final world government, which many consider to be the revised Roman Empire, that will consist of ten kingdoms that will be under the control of the antichrist, and the antichrist himself, which will come from one of the ten kingdoms.