OAC: On Approved Credit
You've likely heard this term on vehicle commercials when they're selling their amazingly low monthly payments or their 0% interest for 24 months deal. BUT, you only get these payments/rate OAC. It means that approval for the attractive monthly payment or interest rate is subject to your credit rating.
The better your credit score, the higher your chances are of getting approved for this special offer. If you don't have a great credit score, you're likely not going to get their deal.