What does it mean to write Kun on red paper and stick it on the bedside? Is there a master to explain!

For feng shui, the word Kun is posted in the room, which means that your room is lacking in corners. This behavior is called corner filling.

Generally, the corresponding words and articles should face the corner, indicating that this corner needs it to stand guard to prevent evil things from invading the house.

As for why the word Kun should be used, the terrain is Kun, and Kun belongs to the soil, which means good luck.