I got stuck on the code for a while, but I finally figured out. SPOILERS BELOW!
The first step is to find the locations of the three codes. Once you find them, it helps to say it out loud. "A to B"... "C to D"... "E to F"... eventually, I realized the first symbol represents the Xth slot on the safe, and the second symbol represents the value at that entry. i.e. "slot[A] = B", "slot[C] = D", "slot[E] = F".
That said, I am currently stuck on the moment a bit after. Good luck with your playthrough!