What does the old horse mean in the old almanac?

Ma Chong: On this day, people who belong to horses should avoid using "chong", namely meridian, ugly line, Shen Yin, You Mao, Chen Xu and Hayes, and then match the twelve earthly branches with the zodiac, namely mouse, ugly cow, yinhu, maotu, dragon, snake and wutu. Therefore, every Children's Day, and the rush at noon, are "running horses"; Yin, Shen, that is, "Running Monkey", is set up in this part of the yellow calendar to tell people not to choose those days that conflict with their genus.