If it is marble, Check if it is polished (shiny). If it is polished check if is a natural created polish or a surface polish applied to the stone. Has the marble dulled in any area and if so why? Spillages etc?. Are there any stains in the stone that need to be removed, you will need to check what exactly the stains are before you can say that you can remove them or not (and then get training on how to remove them). DO NOT touch the stone with any kind of acidic cleaner as it will damage the stone, you can clean the stone with an alkaline cleaner as long as it is recommended to be used on natural stone. is the stone scratched and do they want the scratches removed, is the floor level, if not do they want it levelled.
Then find yourself a training course on how to do this kind of work.
Tred Carefully as you could end up buying the floor.
John