The ten horns you saw are ten kings who have not yet received a kingdom, but will receive one hour of authority as kings, along with the beast.
Textus Receptus (TR) - Revelation 17:12 >Καὶ τὰ δέκα κέρατα, ἃ εἶδες, δέκα βασιλεῖς εἰσίν, οἵτινες βασιλείαν οὔπω ἔλαβον, ἀλλ᾿ ἐξουσίαν ὡς βασιλεῖς μίαν ὥραν λαμβάνουσι μετὰ τοῦ θηρίου.