you have installed the package from master, right? Note that it targets partially wrong strings (from master) and the 19.07 build infra and package lists do not know about arabic, so LuCI can't find any description for it.
My first guess is that something related to this is the reason for the empty description. Genuine bug would be if there is no description when running a proper master (or 21.02) firmware.
Thank you for this clarification. I could find the issue in my side. The arabic support package was installed from a local repository that I use for test purposes.
By the way, I have finished the translation in Arabic of few packages in weblate. Will they be reflected in version 19.07 or in the next firmware version?