What does the wall clock mean? Is it to ward off evil spirits or something?

A clock refers to a clock that makes sound by swinging. It is spherical or oblate (the Christmas bell is bell-shaped), with an opening in the lower or middle part, and metal balls or pebbles are placed in the opening, with different styles and sizes.

Bell: a sound generator made of metal. It is also a percussion instrument, shaped like a clock, very small. There are two kinds. A small copper tongue or metal pill hanging on the body, such as a clock used by Chinese national bands, which is shaken to make a sound; The other kind, no tongue, is pronounced by striking a single symbol or bumping two bells, also known as "jingle bells" and "stars", such as most wind chimes. In addition, there are electric bells, car bells and so on. In different forms.

When: describes the sound of hitting a metal object.