what is apple id num

Without knowing the Apple ID password that matches the shown Apple ID, you can't use the iPad.

The previous owner has to remove it from his account first:

How to remove Activation Lock - Apple Support

Hello,

You don't mention any specific issues. Did your friend do all the things in this article first? --> What to do before you sell, give away, or trade in your iPhone or iPad - Apple Support

If your friend did, then read this support article about getting started. --> Set up your iPhone or iPad - Apple Support