Sugar solutions have a neutral pH in themselves, but it makes your body acidic. Why? I'm not an expert, but as far as I understood a sugar solution is completely neutral since sugar can't take hydrogen ions out of the water or donate them in. Sugar is a non ionic compound, so it does not release H and OH ions in the water so it will not make the solution acidic or alkaline.
I keep on reading and seeing charts of how sugars make your body acidic, like this one:

What process makes a neutral pH solution into an acidic one?
I'm not into chemistry at all and therefore the simpler the answer the better.
It is not proven that "sugar makes your body acidic"!

Your body's pH is very tightly regulated by the body's internal systems; it is also different in different parts of the body - the stomach is acidic (1.0-2.5), the intestine are mildly basic (jejunem 7-9) terminal ileum 7.5 reference here. Blood pH is 7.35, and any deviation from this is indicative of serious illness.