SWIFT transfers are payments sent to or received from accounts in other countries or payments that are not in your base currency but are from an account in your country. Transfers between your sub-accounts, Revolut accounts or SEPA EUR payments do not count towards your free allowance. If you need to make more transfers than are included for free with your plan, you can pay a €3 fee per transfer or upgrade to a higher plan.
To make a SWIFT transfer, simply click "Send" on your Business account Home page, click + to add a new counterparty or select one from the list and continue with steps provided. SWIFT transfers are usually sent using IBAN and BIC/SWIFT code. If input fields say something else, i.e. Account number - this should be a better (faster, cheaper) option available and you should input Account number instead.
The same applies to receive a SWIFT transfer.