Like all updates, the Grand 2 KitKat update is also being released in phases and you will automatically get a notification on your smartphone once the update is available. You can also manually look for the update by going to Settings > About Phone > Software update.
As per the official change-log, the new update brings the usual KitKat goodies like album art on lock-screen, camera shortcut on lock-screen, new launcher settings, improved user-interface and stability, cloud-print support and immersive mode. You can also expect to see updated version of Hangouts as well as Downloads apps.
To remind you, Grand 2 was released in India in January 2014 with Android 4.3 and this is the first major Android update for the smartphone.
If you have already updated your Grand 2, do let us know about the experience in comments.