So I tried looking at the image and it was really blurry. I even pulled my screen to 500% and still couldn't see the image that well, but what I did read it said, "by following this example it will get your VPIP near 20%" in your post you said "20% opening."
Your VPIP is how often you voluntarily put money into the pot, basically it's how often you are playing hands. 20% VPIP on average is a good "Range" to be at on average,it includes hands like 55+, A9s+, all Broadway cards K7s+ and Q8s+ If you are saying that it's referring to opening then maybe it's saying because it's -EV to limp you should be opening 20% of your range from X position. Again I can't read the chart clearly but from what I can see this makes sense.