1. Click Settings on the Navigation bar and select Payments & Taxes from the drop-down

2. Click on Add New Payment Type

3. Fill the details and click on Save

Name : Friendly Display Name like " Card iZettle"
Payment Type : Card ( iZettle UK, Europe & Brazil )

Status : Select Enabled or Disabled option whether you want the payment type to be active or not

4. After adding the payment type, it must be assigned to the Store. Refer the following article to know How to assign a Payment Type to the Store?