If your floor gets very dirty you may not be able to clean the entire room before your cleaning pad gets filled with dirt.

Clean pad

faq

Slide upper and lower pieces together following the channel groove and then slide the green locking sleeve up flush with the bottom of the top handle piece. If you notice some streaking as you are cleaning, it means your cleaning pad is filled with dirt. It features ultra-small droplets in a wide-dispersing pattern enabling you to apply just the right amount of cleaner where you need it.

Source: https://marble.com/articles/categories/countertop-faq