Hi,
This means that the font-awesome CSS library which handles the display of the icons is not loaded.
Normally, HikaShop loads it automatically when it loads itself.
So if you don't have it on the page it's either that you modified the database to remove the loading of font-awesome (unlikely), or you modified the HikaShop code (unlikely) to not load it, or your template (or one of its system plugin) is doing something to remove HikaShop's font-awesome library (which is fine for the frontend, but not for the backend) because it has his own font-awesome library built-in.
To me, the last case is the most likely.
So what you could do is disable the system plugins of your template temporarily via the Joomla plugins manager to confirm this, and then contact your template provider for help once you confirm that it comes from the template.