If you mean the little symbol next to the constructor's name, it's computed automatically by Crosshare based on how previous solvers fared at the puzzle.
Yup! You can also click the symbol to get a numerical rating. That's kind of useless on it's own but useful to compare between puzzles. There's more to come in terms of documentation about how this all works, allowing you to see how your own solver rating progresses, etc.
MFC 4:37 · 2021-08-24T19:41:41.614Z
Thanks a lot. I’m just starting out here and this is such a great site! I didn’t realize the symbols were clickable to find out more about the difficulty. Thanks!