This would typically just show the name of the app. The (5) suggests you somehow managed to have multiple versions of it, hard to say more without looking at the computer & registry.

I was a bit stupid here - I assumed Zotero had generated it while, as dstillman says, it's just a shortcut. When I looked in my taskbar folder (live and learn, I didn't even know there was one) there were four more instances on the shortcut. Now they're deleted and the minor annoyance is removed.

Thanks d!