Shell

I've never used most of these, but here are the important ones:

Wall Thickness: Line Width (Quality) * Wall Line Count. Basically, the outer shell of the 3D print has a certain thickness before the Infill starts, you get to set this thickness with this setting. A higher wall thickness would lead to a stronger print.

Top/Bottom Thickness: Same idea, do I really have to explain this?

Top/Bottom Pattern: The pattern of the layer creation (I've never changed this, but maybe Concentric would be better for circular parts)

Enable Ironing: This is a really non-important setting, but it literally just makes the print slower and maybe marginally smoother. I tried it once but wasn't noticing any major differences. It works by using the hot extruder to remelt the plastic of the top layer to smoothen the layer lines, purely aesthetic, no structural use.