What does it mean to draw a yellow symbol at the entrance of the hall?

Huangfu is a spell in Maoshan art .. Maoshan Taoism is a mysterious Taoism in China legend. Putting it into practice can exorcise evil spirits and make people feel awe. At the beginning, Maoshan art was also called "the art of jade girl and western gods", which was witchcraft. Now there is no such person. In modern times, people's newly rented houses or newly built doors have yellow symbols. Is this feng shui good? Let's take a look at the Feng Shui at the gate.