Woodshedding, or just "shedding" for short, is a musical slang term that means "to practice." Originating from jazz musicians but used in all walks of music life, the term literally means to go out to the shed and practice where no one can hear you or bother you. Woodshedding can be done alone or with a group of other focused musicians. Concentration, dedication, and consistency are requirements.
The term woodshedding has also given rise to calling one's instrument their "ax" and the phrase, "I need to work on my chops."