SEPA transfers represent a way to make payments denominated in euro to bank accounts within the Single Euro Payments Area (SEPA) zone.
There are currently 34 countries which belong to SEPA: 28 countries that are part of the EU, and Iceland, Liechtenstein, Norway, Switzerland.
The way SEPA transfers work is very simple: payment details are usually provided in the app (like it is done in Kriptomat, where you can also download a PDF with details) or via email. These details are then used to make payments, usually via an online banking system.
It is a safe and cheap way to make payments. It uses the IBAN (International Bank Account Number) as a standardised way to represent a bank account number.