System updates (and full installer apps) don't show up in the App Store since Mojave - only in the Updates pane in System Preferences.
Having an OLD system update appear in the App Store is certainly a glitch in the system.
It won't update on Mojave, so "how can you resolve this?"
Is there an option to "Hide" the update? You ARE in the App Store, so you should be allowed to hide any update that appears there.
Finally, if you are completely annoyed by the appearance of that old update, what happens if you try the Actualizar/Update button. It can't install, but choosing Update may cause that notification to reset (I think)
There have been security updates, but the OP shows a system update. Last Mavericks update version 10.9.5 was released September 2014 (as it shows on OPs screenshot)
Crazy that it appears on a system where Mavericks is not booted and running. I don't believe that Apple will push a system update when that system is not even running, and even if ANOTHER non-booted partition or drive on the Mac has that system installed.
@donvito4ever - Do you have any other drives inside your Mac Pro, or attached externally, that would have Mavericks installed as a bootable system?