Suops is a subscription manager which was an attempt to recreate the Collections feature that Google removed long ago.
Its built to display directly onto the YouTube webpage right above your subscription list. Cool right?
The extension can add, modify, rearrange, and delete groups that you create. You can feature anyone from your subscription list for the groups.
That's about it. It's a replacement for the Collection feature that used to exist on YouTube and tries to be as seemless as possible with the YouTube website.