Hi Harry, welcome to MLF
It depends on what kind of payment mechanism you are putting in place. If want to take card payments online, or offline using a credit card reader, then your bank will need you to set up a merchant account. The merchantt account is used to authorise customer transactions, collect payments and then transfer to your bank account.
There are banking costs associacted with this, but it does give you a much more professional image, as well as allowing you to offer many forms of payment.
You could just use Paypal, which doesn't require a merchnat account, but this can scare customers away.
That said, there are plenty of businesses that only use Paypal, so its down to the type of shop you want to open. You could always put a toe in the water, then apply for a merchnat account at a later date.
Hope that helps.