Move mouse pointer to the left corner of a page and click the button that will pop-up in order to scroll the page to the very top. You also have a capability to return back to the position from which you scrolled up by clicking "DOWN" button when you're on top of the page.
The add-on resembles the UP button you may find on some sites with long pages. Also in Opera Mini (when swiping up) there's a pop-up button with same function. When you are reading a web site with lots of text and scroll down most likely you miss a quick way to return to the top of the page and reach site navigation.
The extension can be useful when drilling down Facebook News Feed, reading Twitter trends or using News portals and Blogging sites.