Google bought Motorola Mobility back in 2011 for a whopping $12.5 billion but now they're selling the handset part of the business to Lenovo for only $2.91 billion, a huge loss on Google's part.
Google bought the company in hopes of acquiring some important patents that would help bring in a cash flow from royalties. Unfortunately the patent portfolio was not as great as they hoped.
Motorola Mobility has been making making massive quarterly losses ever since Google bought so it's sensible to sell off the handset division to a company which wants to actually do something with it.
This will help Lenovo place a better foothold in the western mobile markets and hopefully they can bring back the company to making iconic smartphones like it used to.