The tone controls would be set based upon the music being played. When playing clean funky guitar parts the guitarist may want to make use of higher frequencies so would set the tone to a higher setting. For a bluesy guitar solo a muddier sound could be the preferred sound so the tone would be dialled lower.This switch selects which pickup is being used. On Les Paul style guitars, there are 3 positions that can be selected. The neck pickup is labelled ‘Rhythm’ and the bridge pickup is labelled ‘Treble’