JavaBean Listerner Naming Rule

[Xyz Abc]

Hi, I am not understanding this one:
The book states :
"Examples of valid JavaBean naming rules are"
public void addMyListener(MyListener m)

And invalid ones are:
public void addXListener(MyListener m)

Now I know that MyListener cannot be resolved to a type in the invalid case. But why is the first one considered valid?
And what exactly does "Cannot be resolved to a type" mean?

Thanks in advance,
[ December 01, 2007: Message edited by: Xyz Abc ]