the ten horns are ten kings: This number might refer to ten specific individuals, or it might symbolize that this kingdom lasted through the reigns of many kings (compare Revelation 13:1).
Then another king, who is the little horn (Daniel 7:21), will defy the Most High. He will oppress the holy people by:
speaking against the Lord,
interfering with their worship,
trying to force them to follow his religion, and
constantly threatening them.
a time, and times, and half a time: The text does not clearly state the length of time. However, the period of oppression for the holy people will be limited and will come to an end suddenly and unexpectedly.