Can someone explain the following code to me?

Question

I am following along with the Rails 3 in Action book, and it is talking about override to_s in the model. The code is the following:

def to_s
           


        

Answer 1

Actually admin? is a function(probably defined somewhere in controller/helper method or model) that return boolean(true or false) and next question mark is just like a if condition

if admin? == true
 "Admin"
else
 "User"

first portion before ":" is for true case and other is for false case