1) "And I stood on 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. 2) And the beast that 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 (throne) and great authority. 3) And I saw one of his heads as it were (slain) wounded to death,(εσφαγμενην), and his deadly wound was healed: and all the world wondered after the beast."
Quick Summary: John is instructed to document or record events which he had seen, and things that are, and the things which shall be hereafter. (Revelation 1:19). After the seven letters to the seven churches, John is shown a door in heaven and is taken in the spirit. The majority of Revelation consists of futuristic events, events that extended far beyond John's 95 A.D. world vision. These events will transpire during the tribulation moving the reader forward into the Great tribulation period.
And the dragon was wroth with the woman (Israel) and went to make war with the remnant of her seed, which keep the commandments of God, and have the testimony of Jesus Christ. Rev 12:17 (See also Genesis 3:15)
After Satan declares war on the Christians and the Jews. John is shown the rise of a beast kingdom which he documents as previously instructed. John is standing on the sands of the sea 13:1, witnessing the rise of a beast with seven heads and ten horns in the end of days. Several translations such as Darby document the dragon aka: Satan standing on the sands of the sea orchestrating the rise of the beast kingdom as John bears witness.
And I (John) stood upon the sand of the sea and saw a beast (kingdom) rise up out of the sea, having seven heads (four beast kingdoms and three non-beast kingdoms) and ten horns (kings), and upon his horns ten crowns (authority, power), and upon his heads the name of blasphemy.