Activation Lock Problem
If you purchased the device second-hand, then it is useless without the Apple ID and password to which it is locked. If you don't have it, can't remember it or cannot get it, then the device is useless to you. Try to get your money refunded, if you can, or take it to an Apple store for an exchange provided they will help you. If you are the original owner then take the device, a copy of your purchase receipt and identity proof to an Apple retailer where they may be able to assist you.
Find My iPhone Activation Lock
If you can't activate your iPhone - Apple Support
Hmmm, got an iPhone from somebody likely means it is a lost or stolen phone, and you have probably lost your money.