Activate iPad
Activate iPad
This iPad is currently linked to an Apple ID (b●●●●●@gmail.com). Sign in with the Apple ID that was used to set up this iPad.
iPad, iOS 8.2
That is activation lock, you need to use the account that was being in Settings > iCloud to reactivate it.
If it's your account then type in it and it's password. If you can't remember your id : Recovering a forgotten iTunes Store account name - Apple Support or How to find your Apple ID - Apple Support
If you bought the iPad used and it's still linked to the previous owner's account then you will have to contact the previous owner and ask him/her to remove the iPad from their account : Find My iPhone Activation Lock: Removing a device from a previous owner’s account - Apple Support