ISO represents the sensitivity of the "film" towards light. Higher values means you can take photos under darker conditions, at the expense of image quality (noise) . FF are capable of reaching higher ISO values without too much noise- one of the main advantages of FF, which you have!.
In general, for a FF, ISO50-400 is very good for morning till afternoons. ISO640-1000 for dawn and dusk. And ISO1600 and higher (my max max acceptibility is ISO5000 on my D800; ISO3200 on the D90) for indoor shots. Try not to be too worried about the ISO values la haha

Aperture values, depending on your lens, is usually good for normal shots @F2.8-F5.6.
Aperture values lower than F2.8 are in general used for portraits (better bokeh), and under dim conditions (like your food shot above [but for cameras with lower ISO performance]).
Higher aperture values F8 and above are usually used for group shots, macro or landscape shots to get everything in the frame to be not-blurred.

Just need to learn how to "balance" in between ISO and Aperture

These pretty much covers the basics to use the A mode on your camera, go try it out, practice makes perfect yo~

Guy On The Street by Pro3363, on Flickr