This update, iOS 8.2, will bring Apple Watch functionality to the iPhone and a few other features. It will bring back data points to the Health app and short descriptions for the measurements available. A companion app, which has not be released in any of the beta versions, will likely come with the update too.
The report also says that iOS 8.3 will follow and come out soon as well. There have been two betas already released to developers and four are planned. Apple is also rumored to open up public beta testing during the middle of this month. They will likely start with iOS 8.3. In addition, iOS 8.4 is also expected out before iOS 9 is announced in June.