Like Michael says, the top chart is just hypothetical, and it only uses some random exposure, and is NOT about any specific exposure condition. Instead, it tries to show two concepts.
It is an Equivalent Exposure guide, indicating that f/2.8 at 1/1600 sec, or f/4 at 1/800 sec, or f/5.6 at 1/400 sec, etc, etc, are Equivalent Exposures. You can choose any one of the combinations to keep the same exposure (but as is, the chart itself is NOT about your specific local exposure). You might prefer one aperture for depth of field, or one shutter speed for stopping motion, etc, etc. You choose the Equivalent Exposure best for your purpose.
Also, it shows that "stop" relationship to both shutter speed and aperture. 2x shutter speed is one "stop", same as one aperture stop is one stop. If you think of the chart as a slide rule, and imagine one scale is moved to slide it one step horizontally relative to the other, then the way it lines up then shows Equivalent Exposures of that new exposure, shifted "one stop".
The chart is about the Equivalent Exposure concept, an extremely important concept, but then we don't need the chart. Our camera viewfinder shows the numbers being used. In camera modes other than Manual, when we change shutter speed or aperture, the new value of both values is shown.
Sunny 16 is about some actual exposure, but you should look up Sunny 16 again. Bright sunshine is a constant, and Sunny 16 also tries to account for degrees of overcast (judged by the shadows cast). In the old days before light meters, Sunny 16 is all we had. But it is difficult for us to judge degrees precisely (like 1/3 stops). It worked well with negative film, which had wide latitude, but our guesses were typically just "ballpark", and digital really needs to be more precise. Your camera light meter should work better than Sunny 16, BUT Sunny 16 is always a good guide to know to decide if your meter value is reasonable or not. In reality, bright sun is normally EV 15, which is ISO 100, 1/125 second at f/16.