Howtogeek posted a guide about enabling icons on the Ubuntu System Menu

If you've spent more than five minutes using Ubuntu, you might have noticed that the System menu doesn't have any icons, but the other ones do. Why? Who knows! Either way, here's how to enable those missing icons.
In case you didn't notice, have no idea what we're talking about, or just want visual confirmation, here?s the system menu by default:

  How to Enable Icons on the Ubuntu System Menu (Minor Annoyances)