The top area only lists all the possible views that you can use on the checkout.
The bottom area has several grey zones (4 on your screenshot). Each grey area is a step of your checkout. Inside it you can the views that will be displayed in the step.
You can move the views inside a step zone, around different step zones, from the top area to a step zone, from a step zone to the delete icon.
You can see that the last grey area is empty. If you add a view in it, it will become a new step of your checkout automatically. If a step is empty when you save the configuration the step won't be used on your checkout.
In your case, your checkout has three steps, the first one with login/shipping/payment/status/field, a second step with address and a third one with cart.