Just an FYI that 10x5 means its a 10 inch diameter prop with a 5" pitch, meaning for every revolution the prop will move forward through the air 5 inches (this is theoretical in practice its usually less)

The higher the pitch is like running higher gears in a car, it will go faster but not accelerate or pull as well. Lower pitch will accelerate better and hover better but not be as fast on the top end. Also engines make thier ideal power at a certian rpm so the trick is to find the diameter and pitch that put the engine in its accepable rpm range and performs the way you want it to for the airplane its on. For instance a war bird may have a smaller diameter high pitch for top speed where a 3d plane with have a larger diameter but a lower pitch for the same engine so it can hover and accelerate but not go very fast.