I didn’t make a copy. I just made a group and then moved it away to show that there is more geometry.
Among other things, groups and components are objects used to isolate entities from each other and in the case of raw geometry, prevent unwanted connections. For example you don’t want the furniture to become part of the walls so you wrap up the chair geometry in a component container. You could put your wall geometry into a group or component container to prevent the doors and windows from merging with the walls. The same would apply to the cabinet work in the kitchen.
Tags are properties applied to components and groups primarily to allow control over visibility in scenes in SketchUp or in viewports in LayOut. The accepted best practice is to leave all raw geometry untagged. The pencil icon remains set for Untagged in the Tags panel (in previous versions of SketchUp the term ‘Layer’ was used instead of ‘Tag’ but they are used the same way.) Then you assign other tags to just the groups and components in the model.
If you want to change which objects are displayed in the viewport in LayOut, you can adjust things in the SketchUp Model inspector panel.
This leaving the geometry untagged and creating all geometry as untagged makes for an easier workflow because you never need to worry about which tag is active when you are editing a component or group.
Another use for tags is to assign dashes if you want to use them like I showed yesterday. Additionally you could show objects in different colors based on their tags if you wish.