Marble is a very soft stone and it is much softer than granite. It is also highly porous, so it is very easily etched by acids. (vinegar, tomato juice, orange juice, etc) It's also prone to develop water stains or spots, such as marks left by drinking glasses, or water spots after mopping.
Clean your marble stone surface with a soft cloth or mop using pH neutral cleaning solution. Always wipe off any spills immediately as they happen. Never, ever clean this floor with vinegar, as you will destroy the finish. I use Lustro Italiano cleaner from
http://noads/products.php which works best for me.