Okay, so APACS stands for "Association for Payment Clearing Services". Now, when grown-ups want to pay for things, they usually use something like a credit card or a bank account. But when they do that, they're not just magically moving money around. There's actually a whole bunch of computers and systems and rules that make sure the right amount of money gets taken from one person and given to the other person.
That's where APACS comes in. They're like the bosses of all those computers and systems and rules. They make sure everything happens smoothly and securely. They also come up with new ideas to make paying for things even easier and safer.
So the really important thing to know about APACS is that they're the ones making sure your grown-ups can buy you toys and treats without anything going wrong!