The account balance refers to the net amount which can be find out after calculating the debit and credit from the balance sheet . It mostly includes that amount of money which can be owed to the third party such as credit card company , mortgage banker etc.
For example , with the help of credit card a person do shopping and he purchases three items costing $200 ,$100 and $50 , at the same time he also return one item costing $20 . The account balance includes all the purchases that is $350 , it also includes that item which he returned for $20 . The net of the debits and credits is ($350-$20)=$330 . This amount is called account balance.