This question appiles to the mechanical movement. To understand what this is and how it differs from a quartz movement we suggest you first read this and this. An automatic movement is simply a mechanical movement that has a built-in feature to wind up the mainspring (read replenish the power of the watch). Usually this is done by a winding rotor which is the thing that moves around when you look at the watch through the caseback. This rotor moves as the watch on your wrist moves. A manual-wind or hand-wound movement is basically a movement without this winding mechanism (pictured above). So as the name suggests you have to manually turn the crown (in most cases) to wind the mainspring and add power to the watch.