When you start scrolling down, the scroll-to-top button will become visible. And by clicking on that button, you will get back to the top before you know it! If you use this on a long page, the button will stay fixed to the bottom right and be visible all the time. It is something that can be very useful on long pages.
It may be a tad confusing that when you first import this component, you won't see much! - unless you locate it in the Element tree and open the wee eye icon. The component should preferrably be added to the upper part of the page to make use of the min-height of its containing .component-visualizer.
If you find that it doesn't seem to work on mobile phones, try increasing the min-height of the page. As much as 200vh may be necessary.