Just faffing around with the cam settings on my d500 and its got "ISO" and "SPOT FOCUS", what do these do?

 

ISO is the measure of how light sensitive a film is. i.e iso 200/ iso 400 etc. The higher the number the more sensitive the film is so the less time it needs for the exposure. So iso 400 is good in bright sun etc.

Also the higher the iso the more grainy the pictures become and the less you can blow them up

Spot focus is more than likely you can set the camera to focus on a single point. usually in the middle instead of a general focus for the whole area.

HTH