Secured area

In the "Head First Rails" book, it has the following as part of a
method:

authenticate_or_request_with_http_basic("Ads") do | username, password|

It mentions that "Ads" is: This is the name of the secured area of the
website - the "domain".

Provided that the authentication is meant for the "edit" and "update"
methods.

So, how is ("Ads") the name of the secured area of the website? Is it
JUST a name we enter? I entered for example ("Advertisement"), but
didn't notice the effect of this name after logging in.

What do you think?

Thanks.