There are few different types of labels that Amazon provides for sellers. Please see information about each below: Amazon Customer Orders - These are orders to fulfill the customer. You could leave the layout as "default" format, which will produce a label in 4x6 size for the label printer and other thermal printers.
Amazon ASIN product Labels - These are labels to stick on products before sending them to Amazon. Amazon FBA Labels for Outside the Box - These are labels to stick outside of the boxes of your products that will be delivered to Amazon's warehouses.