My mother put soybeans and rice in a cup beside my bed. What do you mean? Is it an evil spirit? Or transshipment?

According to legend, soybeans and rice can ward off evil spirits. In folk customs, 5~7 grains of soybeans and 5~7 grains of rice are often put in cups and then placed under or beside pillows to ward off evil spirits. Soybeans are chosen because they are yellow, which represents righteousness. Soybeans are one of the five grains, so there is a folk custom that soybeans can ward off evil spirits, and so is rice. There is also a folk custom that rice can ward off evil spirits, because rice is an essential food in people's lives, and it can have some power, so sometimes when something happens at home, someone will "ask for rice" for divination. In addition, there are five-color beans to ward off evil spirits, namely red beans, black beans, mung beans, soybeans and white beans. This practice is usually to avoid "ghost pressing the bed". However, I think this is just a folk custom. I think it is illogical to say that it has the function of exorcism. Soybeans and rice are just ordinary things. What is the ability to ward off evil spirits? To ward off evil spirits is to fight against those things in a sense. If the aura (mana) of evil spirits is higher than those of those things, then evil spirits will play a role in evil spirits. If those things are more powerful than those things, then the evil spirits will be ineffective. How can beans and rice compete with those things that have no aura (magic)?