Apple today released iOS 8.2. Among several bug fixes, Apple included new functionality for iPhones to work with the Apple Watch. After installing, you see a new Apple Watch app on your home screen. Since the Apple Watch has not yet been released, this currently just links to Apple advertising apps, but in a little more than a month it will be used to configure your device and change settings.
As always, be careful before installing the new update. I have installed it on my iPhone 6 plus and experienced no problems, but every situation is different. If you haven’t already backed up your device, see our article that explains how to use iTunes to backup manually.