First a note about the structure of the conversation: in various translations we may find the indication above Song of Solomon 6:10 that these are the words of the daughters. However, there is nothing in the text to indicate this. It is much more natural to think that the husband is speaking here. He now expresses how he longs for his wife, how he burns with desire so much that he would like nothing better than to see her approaching there in the distance.
When he sees her in his mind’s eye, she already becomes clearer to his eye of desire—just as at dawn, you see the light getting clearer and stronger. When he sees her before him like this, she is as beautiful to him as the moon. The moon is a bright light in the dark, and the light of the sun is called good in the Bible (see Malachi 4:2; Revelation 12:1).
The beauty and purity of his wife overwhelm him in his mind. It makes such an impression on him. She looks like a strong woman, as if in her the husband sees a great army of standard-bearers before him. The woman is compared to someone who carries the banner, someone who is part of an army.
10 “Who is this who looks down like the dawn, beautiful as the moon, bright as the sun, awesome as an army with banners?”