Good morning Kim,
Great question!
The Qiime 2 files like .qza and .qzv are just .zip archives. So to open one up, you can simply rename it as a .zip file, then extract it.
mv shannon_vector.qzv shannon_vector.zip
unzip shannon_vector.zip
Of course, you could also rename it in the folder and simply double-click to extract. That's probably easier than the command line 
Once you have extracted it, you can open up the folder and find the Shannon vectors inside.
Let me know if this helps,
Colin