There's a bunch of unshielded copper wire in a light switch - what is it and what does it do?
You are probably looking at grounding wire, which is typically sheathed in green or is bare.

The bare wire serves as the equipment grounding conductor as a safety precaution.  In the event of an electrical fault, the equipment ground will prevent you from becoming shocked and injured by coming in contact with bare metal in the box or on the metal casing of the switches or other receptacles (if there was an electrical fault).

It is perfectly normal and nothing to be alarmed about, it is a safety feature.