For refunds, there are two situation how you will handle the refunds, depending on the payment gateway.
For Stripe Connect, you can click Refund, and the system will connect with Stripe API to refund back to customer banking account automatically. More about refunds for Stripe here.
Stripe MY, Stripe SG, SecurePay
For managed payment gateway, you can click Refund, and we will process it as part of your settlement. You will receive full amount back, including any payment gateway fees already levied by payment gateway. We will bear this cost for you.
You may do manual bank transfer back to your customer banking account to settle the refund to customer.