What does the nine-star "heshi" in Feng Shui mean?

That is determined by the yin and yang numbers in Luo Shu. The rules of Luo Shu are as follows: Wear nine shoes, three on the left and seven on the right, two and four as shoulders, and six and eight as feet. That is to say, the sum of the yin and yang numbers of each corresponding hexagram position is ten. Hetu is the mother of Bagua, and Luoshu is the source of regulating Qi. Therefore, it is academically believed that the nine-star conjunction according to Luo Shu Feibu can correspond to the nine stars.