What is the line on the arm? What does the line on the arm represent?

What does the red line on the girl's right arm mean?

The red line indicates: 1. Also called "red line". 2. Red silk thread. 3. The legendary female Xia's name in Tang Dynasty. Tsing Yi, Xue Song, our ambassador to Luzhou, took the back of the watch and put it in the room. At that time, the new era merged Tian and Luzhou. Song was depressed day and night, and there was nothing he could do. The red line is to go to Weixian at night, go to sleep in the fields, and steal the gold box at the bedside as a warning. Fu Song's suicide note was inherited with a gold box. Inherit and send an envoy to apologize and be willing to marry in-laws. The red line also resigned, and I don't know what to do. See Ganze's storytelling. The Red Line of Jiao Yuan in Tang Dynasty. It is said that the marriage between men and women is mostly decided before, as if there is a red line secretly tied. Conclude a marriage or matchmaker agreement by name. 5. Borrow a dowry. 6. Metaphor refers to the right idea from beginning to end.