The page lists your measures and columns from it and checks every name, so the script only refers to fields that exist.
Both give you a slicer that changes what a visual shows. They differ in where the result can be used.
Select a field to add it. The label is what the slicer shows; the order is the slicer’s order.
Nothing picked yet.
Checks run as you go. The test query changes nothing in your model; the TMDL script adds the table.