Question

Why are bells are made of metels and not from wood

Answer 1

 Metal is much denser and stiffer than wood, so it stores more kinetic/potential energy per amplitude of vibration of the surface. So it can support the same sound amplitude for longer.
Metal is much harder than wood, so (if you want) you can hit it with much harder objects without damage.

Answer 2

Bells are made of metals and not from wood because non metal i.e. wood is not sonorous i.e. they do not produce ringing sound when striked against a surface while metals are sonorous i.e. they produce a ringing sound when striked against a surface.

Hope you will find it helpful!