Complex sentence: The bunch of wool or plant fibers is held in the left hand; with the right hand the fibers are drawn out several inches and the end fastened securely in the slit or hook on the top of the spindle.
Split into simpler sentences: The bunch of wool or plant fibers is held in the left hand. With the right hand the fibers are drawn out several inches and the end fastened securely in the slit or hook on the top of the spindle.