I bought a device from someone and it wont let me get in it because of activation lock and we both dont know how to do it

Return the phone for a refund. The "someone" that you bought the phone from was not the owner. The phone is likely stolen.

The phone is totally and completely useless without the correct Apple ID and Password.

To get Apple to help, you would have to submit paperwork....sales receipt, serial number, agreement, etc. to prove that you were the original owner of the phone.

To verify, look over the Apple Support document linked below. Skip the first few parts because you don''t know the Apple ID or Password of the original owner.

How to remove Activation Lock - Apple Support