Your e-commerce website can be enabled to accept credit cards via a 'payment gateway'. A payment gateway is a third-party company that provides secure link between your Zeald website and your Merchant Account. They are carefully vetted by the credit card companies to ensure they have a very high level of security, and handle the credit card so that you and your staff never even see it. This makes it much easier to be PCI Compliant.
You will need a merchant account that will accept online credit card payments in the currency you do business in. Even if you have a current merchant account you need to check it will be able to accept and support online transactions in the way you would like.
There's also a number of other payment methods you can support: eg Direct Credit, Purchase Order, even Cheque
For more information on how to set up the various alternative (non Credit Card) payment methods see the help topic Set Up Alternate (non Credit Card) Payment Methods