the slider_object is basically like a listbox that controls a variable - you can set it to any intervals, say 5. You set a range, say 0-100. So you can just use that slider to assign to your variable the values 5, 10, 15, 20 ... or 100.
You can use it, e.g., to quickly change some value used in a calculation in the charts so that the chart shows something different depending on the position of the slider_object.
You could achieve the same effect with an Inputbox, of course - it is just a more elegant way.
You might want to include the current value of that variable in the title of your chart so the user can see at any time what it is the chart is showing them.