What does evil west and evil south mean in the perpetual calendar?

"Shaxi" and "An Shan" in the calendar mean that you can't go west or south on this day. Going in that direction will lead to disadvantage.

Three evils refer to robbery, disaster and age. Among the twelve earthly branches, the fire is born at noon, the fire in the south is flourishing, and the north (the ugly sea) rushes to it, which is the three evils (the sea is a robbery, the child is a disaster, and the ugly is an old evil). When applying to the Water Bureau, the north is full of water, and the south (at noon) rushes to it, which is the three evil spirits (robbery, disaster at noon, not the old evil spirits). Haimao did not join the wood bureau, and the wood flourished in the east, and the west (Shen Xuyou) rushed it, which was the three evil spirits (Shen for robbery, West for disaster, old evil spirits). In the ugly alloy game, the west is for the rush, and the east is for the three evils (Yin is for robbery, Mao is for disaster, and Chen is for the old evil).

Every afternoon, the north is the third year. During the Shen Dynasty, there were three evil spirits in the south. Before the year of Haimao, the west was the three evils in the middle of the year. In the ugly year, the East is the third evil spirit. If the chosen place belongs to the evil direction, the ancients thought it could not be built.