Why does my joint credit union accout statement say credit available?

My dad belonged to a credit union and before he died, my name was placed jointly on his credit union account with him. I think it is because he was scammed by a savvy car dealer and I paid his monthly payment on the account until his car was paid off shortly before he died. Why is there credit available on the statement? What does that mean?|||He might have had an open line of credit or something. Check with the bank.|||maybe you need glasses|||Did he have a revolving line of credit meaning he could borrow this at any time.