If this is the wrong place for this please move to appropriate forum
So I've been surfing the showcase forum looking at other websites and I'm seeing that most of them have a resource tab. What is that?
You can only display the Resources tab IF you bought and installed the Resource Manager as an extra part of XF.
If you did not buy it, don't worry about it.
The Resource Manager stores stuff which is put there by members of the site (conceivably just by the admin) but normally by members.
The 'stuff' can be software to download, documents, pictures. Or it could be tutorials, pages of info, one page articles.
Resources can be paid or free, if paid there can be a link button to go to a payment page.
Members can Rate a Resource, Review it.
Its owner can update it to a better version and the RM tracks that and notifies you if you Follow it.
Variations on the RM are being developed yo use it in other ways eg Articles but these are edits done by members, not supported by thye XF team.