Hi! As of now, Files gallery will display any information that is stored in the image, including IPTC title and description as well as GPS map link (Google maps). You can add this info into images from apps like Lightroom, iPhoto and other apps:
If we are to allow creating descriptions directly in Files app, we need to create an interface for editing and store those descriptions in the folder also (separate from the image). This was not the main intention of Files app, which was designed to be "passive" without affecting the users file-system. However, I believe it will be a future feature at some point.