This stems from a short story-Liuchi Lane: the neighbor of Zhang Ying, the prime minister of the Qing Dynasty, built a house. Because of the dispute between the homestead and the Zhang family, the family flew to Beijing, hoping to say hello to "appease" the neighbors. Zhang Ying smiled faintly after reading the letter from home, and replied in the letter from home: "A letter from home is just a wall, why not be three feet?" The Great Wall of Wan Li is still there today, but I haven't seen Qin Shihuang. "The family was ashamed after reading it, so they gave up their three-foot homestead according to Xiang Ye's meaning. Neighbors were deeply moved to see Ye Xiang's family so open-minded and humble, and they also gave in three feet and became a six-foot lane. This hutong in Tongcheng witnessed the traditional virtue of modesty and courtesy of the Chinese nation.
It means to be polite to others