This, like so many other Italian "recipes," is really a suggestion more than a firm recipe. It leaves things up to availability and your subjective taste.
It is really quite simple. You cut ripe, tasty peaches into slices and add to wine.
Red wine or white wine? White peaches or yellow? Sugar or no sugar? Allow to stand or not? Peel peaches? Serve in bowl or glass? Fork or spoon?
My suggestion, influenced by seeing my nonno Giuseppe savor these in Naples (actually Caserta) a long, long time ago. Ripe slices of peaches (preferably white), peeled. Add to medium bodied dry red wine, not tannic. Add one-half to one tablespoonful of sugar for each peach. Allow to steep, refrigerated, for at least one hour. Serve in wine glass, with spoon.
Feel free to experiment. The advantage of white wine is that it will be a cooler, lighter drink.