When making a withdrawal via bank transfer, you may be asked to enter your IBAN and SWIFT/BIC.
IBAN is an international standard for the identification of an account which is used similarly to local bank transfers, however this is used for international transactions. SWIFT/BIC is a code that is used to identify a specific bank during an international transaction.
Usually you can see both SWIFT/BIC and the IBAN number on your internet banking, or by getting in touch with your bank.