You can add “third-party payment processor” to your shopify to accept payments.
The most common third-party payment processor is PayPal. It's available in many countries. It supports most common currencies. It doesn't have any monthly fee.
PayPal can also accept VISA, Master & AE payment directly. If customers have PayPal account, they can login to pay by PayPal balance. If they don't, they can directly insert their credit card info to make payment. PayPal will also create a account for them and save their info for their future purchases.