A credit card balance of 0 means there is currently no outstanding balance. The available balance of 1 yuan means that the available limit of the credit card is 1 yuan.

The credit card balance is the amount owed by the credit card. Whether the balance is positive or negative depends on the bank's definition. ATM machines of different banks display different numbers. Regardless of whether it is positive or negative, it represents the amount owed by the credit card. The available balance is the credit card limit. If it is a positive number, it means the actual remaining limit available. If it is a negative number, it means there is an overpayment. For example, the balance of a credit card is -1000, which means there is still an outstanding balance of 1,000 yuan on the credit card. The available balance is 25,000, which means that the available limit of the credit card is 25,000. If the available balance is -100, it means that there is 100 more repayments in the credit card, resulting in an overpayment, and no repayment is required in this period.