the ten horns which you saw are ten kings
These are the same ten horns which Daniel saw in his night vision (Dan. Dan. 7:7-8, Dan. 7:20, Dan. 7:24). The ten horns correspond to the ten toes of Nebuchadnezzars image (Dan. Dan. 2:40-43). See Nebuchadnezzars Dream and Daniels Vision.
who have received no kingdom as yet
These ten horns are all on the seventh head which corresponds to the final historic stage of the terrible beast which Daniel saw (Dan. Dan. 7:7, Dan. 7:19-20). Like the ten toes of Nebuchadnezzars image, which extend forth from the feet during the final kingdom, these horns from the seventh head do not arise until the time of the end. An angel gave Daniel the same interpretation: The ten horns are ten kings who shall arise from this [terrible beastly] kingdom (Dan. Dan. 7:24).
they receive authority for one hour as kings with the beast
The association between the ten horns and the seventh head is made explicit. Unlike the kingdom of God which cannot be shaken (Heb. Heb. 12:28), the ten kings will only have authority for a short period of time, and then only to direct it toward the Beast when he rises in ultimate prominence. The Beast rises up as an eleventh horn (Dan. Dan. 7:20) and eventually overthrows three horns leaving eight horns, seven plus himself. The phrase one hour indicates a historically short period of time. The Tribulation period (lasting seven years) is called the hour of trial which shall come upon the whole world (Rev. Rev. 3:10+). When Babylon is destroyed, her judgment comes in one hour (Rev. Rev. 18:10+, Rev. 18:17+, Rev. 18:19+). The phrase differs in meaning from the hour which indicates the time when a pending action has finally come (Rev. Rev. 14:7+, Rev. 14:15+).