An IBAN contains information that banks use to verify your account number, the country of origin of your bank, and other account details. This information ensures that the correct code and account number are input into the bank system.
Failure to which you might send money to the wrong recipient. If the transaction goes to the wrong recipient, their approval will have to be sought first before the bank can make any reversal from their account.
Fortunately, most banks use an IBAN checker, also known as an IBAN lookup, to ensure that valid IBANs are free of errors.