How is PropertyChangedEventHandler used?

How is PropertyChangedEventHandler  used?

Can you tell me what this bit of code in a class' Initalize method does?

There is a class in the project we are working on that has a private Initialize method.  And there is a bit of code in this method that I want to discuss. 

But first, let me describe the class.  The class is defined as something like this:

public class Skoobie : BaseThingy, ISkoobie

So, that means that the class, "Skoobie" has two parents that it is inheriting from.  What are all the implications about this?

Anyway, so the Initalize method is something like this:

private void Initialize()

{

            this.PropertyChanged += (o, e) =>

                {

                     If (e != null)

                     {

// some stuff is done

}

                };

}

Now, "PropertyCHanged" is a member of the parent class "BaseThingy" which is defined like this:

public event PropertyChangedEventHandler PropertyChanged;