“Awwwwhat a cute little diagram,” the stranger said, “what’s its name?”
“Fi qo.   (A misspelling; it isn’t purebred.)”
“May I pet it?”
“Sure, Fiqo won’t bite, but it can have a bit of a bad attitude.”
“As if it’s trying to prove something.”
“Just what is Fiqo trying to prove?”
(Spoiler alert: Fiqo succeeds.)
The answer is a mathematical formula not meant to be tricky, though the general-case role of those black squares (unit sized in this specific case) might take an extra moment to understand precisely.