Great question! With the release of GRIM, a lot of these terms have been clarified, so let me borrow some language!
Disadvantage: Multiple coin flips. If any are Tails, you fail.
Advantage: Multiple coin flips. If any are Heads, you succeed.
So if I have just one disadvantage die (should be coin flip, gotta change that), I will flip two coins, and if either of them are Tails, I fail that “roll”. That goes with triple disadvantage as well.
On the other hand, if I have one advantage die, I will flip two coins, and if either are heads, I succeed that “roll”.
Please let me know if that sounds like it makes sense! And you’re not stupid; this was one of my earlier games so it’s language is a tad bit rough!