As part of its new Google+ sign-in initiative that went live today, Google pushed a silent update to the Google Play Services app to support the new feature, which also brought along a new app called Google Settings. Google Play Services updates in the background routinely, much like the Play Store itself, in order to have phones up to date and syncing properly. The updates don't usually install new apps, but there's nothing to worry about here, the Google Settings app is indeed supposed to be there.
That being said, it doesn't seem all that useful, as it just provides shortcuts to the settings menus of other apps on the phone -- like Google+, Maps and Location. These settings could all be accessed previously, but in order to have everything working out of the box and have a settings area set up for the new Google+ sign-in, Google had to push something out there. We may have preferred if there was some kind of notice of what was going on though.
Going forward it's likely that Google will use this app to house more than just a few settings shortcuts -- and the functionality could easily just be baked into the general OS settings as well. For now, just let it be -- at least the icon isn't too ugly.