"Present balance" is the total amount of funds you have in your wallet. This balance includes any pending cash back that has not been issued. If the cash back is in a pending state it cannot be withdrawn, until the transaction has been cleared.
In your wallet, "available to withdraw" includes the amount that you are able to transfer to your bank or PayPal account. This does not include any pending cash back that has not been issued. You must have a $25 balance to be able to withdraw any funds.