Why does my email address have a number in it?
Your email address is automatically generated, based on your name. If someone has already used that email address, then a number is added to the end to make a brand-new address for you.
See also:
Why can’t I just choose my email address?
I still really don’t like my email address. Can I have a different one?
But I can see that the email address I want isn’t being used. Why can’t you just let me have it?