iCloud activation Password

Only your friend can help you with this problem since it was he that put the Activation Lock on the device. If he doesn't remember the iCloud password, he can go to Apple - My Apple ID, sign in with the Apple/iCloud ID and reset the password. If he doesn't remember the answers to the Security Questions to do the reset, he can contact Apple Support to have them reset:

ACCOUNT SECURITY CONTACT

Best of luck,

GB

There is no way around the password. remember or recover it.

iforgot.apple.com

Toss it in the trash. Without the Apple ID and password of the previous owner who set the code the phone is useless. Find My iPhone Activation Lock