You only have one listing that you will post and that is still showing your choice of carrier.
It may be changed/updated to Simple Delivery which is currently being rolled out across the site.
In future when you list items, they will have Simple Delivery as the only postage option. You can choose to use Evri, Royal Mail - both or just one.
You will pack your items.
The buyer will pay the postage shown on your listing and you will be able to print the label or take a QR code on your phone to a Post Office or an Evri drop-off point.
"There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.”
Søren Kierkegaard, Danish philosopher (1813 - 1855)