Could use an explanation of the notation for an oracle adversary

Question

In the definition below, what exactly does it mean for the adversary (not even sure that's the correct term?) to equal one?

$$ \underset{K}{Pr} \left [A^{F_k(\cdot)} = 1 \right ] $$

Source (Page 22/35?) or Imgur Link

Thanks in advance!

Answer 1

This represents the probability over all $K$ that $A$ given an oracle access to $F_K(\cdot)$ outputs 1. You usually compare that to the probability of A ouptputting 1 while having oracle access to a random function and the difference tells you how well $A$ does at telling $F_K$ from random