Copper shows you various important in interesting info about the parts that make up your PCB. Tap on the info icon in the component browser as described in this article: Part and signals list.
Hiding a part from the BOM
Some parts are not really parts, they are just a pattern used to describe something on the PCB. A good example for this are mounting holes or test points. They are a part in Eagle definition, but nothing that you need to order from a distributor. To clean your Bill of Materials of these items, you can switch the "Hide from BOM" to on. This part will be hidden from the BOM now.
Please be cautious with this option. If you activate this setting for the wrong part you might not order all parts necessary to assemble your part!
Choose a 3D part
Tap the "Choose 3D part" button to find and select a 3D part and assign it to the footprint. Copper comes with an extensive part library that is constantly filled by other users using the Mac version of Copper.
Setup 3D part
If you already have assigned a 3D part but need to adjust some settings, tap this icon.
More details on adding and fitting 3D parts can be found here.
Remove 3D Part
Tap this icon to remove the 3D model from this footprint.