I have a security lock number to type in to enter my iPad. I want to allow a friend to use the iPad but without entering via my number to my data etc. One can do this I think on a MacBook when the locked screen ask for 'user'. Is there a similar possibility on the iPad?

Don think there is any way to do th at.certainly never seen that option on any of my iPads.

Take a look at some of the child lock apps that limit access

Ios devices are not designed to "share"

The operating system has no features supporting that.

You could enable perantal controls to limit acces but that would disable alot of your own freedom as well.