Stains on a vinyl floor are hardly ever permanent. They occur only when a strong chemical substance has been left on a floor for too long. This is definitely something you should try to avoid.
Always mop up any spilled liquids and dirt as soon as possible. The longer you leave anything on the floor, the greater your chances are of stains. Difficult stains can be removed with acetone or a special cleaning agent. Wipe thoroughly with a cloth and your floor will be clean again.