What is this option for "Watch Milestone" ???

If I could post an image I would but in my YT Studio, Channel customization settings, and the "Home Tab"

I see a section I have called "Watch Milestone" that reads "Motivate your fans to help your video reach the next view count milestone.  "

what the heck is this? i see no way to control it settings, i have no idea what the next view count milestone means for "your video" ... it's just weird.

does anyone know what the heck this is?