What does Daniel 10:13 mean?

'But the prince of Persia’s kingdom resisted me for twenty-one days. Then Michael, one of the chief princes, came to help me, and I was able to leave the kings of Persia behind.' Daniel 10:13 - Modern Text Bible

(There’s a spiritual battle going on behind the scenes. The 'prince of Persia' refers to a spiritual being opposing God’s messenger, and Michael (an archangel) intervenes.)