Sharpness, in the simplest terms, adjusts how the camera processes the pixels in the image. The pixels can either be very defined and make edges clearly pronounced, or much softer and blended together.
To adjust your sharpness settings, go to settings, then Advanced settings.
Scroll down to Sharpness, which you can then adjust between High, Medium, and Low.
Low sharpness may be ideal for low activity events (panels, meetings), whereas high sharpness would help better define objects in higher activity events (dance recitals, sports). The default setting is Medium.