What is this hierarchy of an empty and a collection, and how do I get to the mesh inside? I got some plants from here and they are gorgeous. However, I ended up moving some files and the textures broke, so I diligently went back and fixed them one by one. The last bit was doing the stems and leaves of this plant here:



Now, the screenshot is what I see when I click-select the leaves. An empty at the bottom (see the stems, I think that's an empty, at least…) and a dark-orange selection border around the leaves. I figured the empty and the leaves mesh were parented so I looked into the side-thingy and this is what it looks like:



Now, that orange icon is one I'm not familiar with, and I can't find anything in the docs. I can't go into edit mode: no matter I many times I press TAB, the mode never changes, and in fact nothing other than Object mode is available in the top-left drop-down control in the viewport.

Suffice to say, this isn't giving me access to the material, so I can't fix the texture. I'm genuinely stumped. Any pointers?
The orange box icon is a Collection Instance.  


It can't be edited, it's just a link to some other collection, that needs to be edited.
To import assets from other files, make sure to use  File > Append the collection.  
Then it's imported with all objects as separate items.


Importing all objects as separate items using File > Append