Your available balance is the amount you can spend. If you want to take cash out or pay with a debit card, you can spend your available balance. You might think of it as "funds available to withdraw."
That number may be lower than you expect. If recent deposits do not show up as available funds, there’s a reason. Checks take time to clear, and banks often hold funds for a while.
While your money may not be available yet, it probably shows up in another place.
You’ll probably see other balances in your account. In addition to funds available, you may find an "account balance" or "running balance". This is all your money, but some of it is not available to you.
Why can’t you spend your money? The bank may have frozen or "held" some of the funds - if you recently made a large deposit, for example. There may also be other claims on that money. If you use the bank’s bill payment service and you’ve scheduled a payment to go out, those funds may be removed from your available balance so that you don’t spend more than you’ll have.