Believe they are referring to Activation Lock.
If you have proof of ownership of the activation locked device, Apple might be able to help. But otherwise, it's an expensive paperweight.
Apple ID should be listed in Settings, at the very top of the iPhone (your name here section). Tap that to see email address used for the account. Or App Store app: tap the silhouette at the upper-right to get same information.
You can go to appleid.apple.com to try to reset your friends account password, if that's an issue.