Ummm...
* is a typeglob, which means in a way "Everything named ...".
So *foo is everything named foo: $foo,@foo,%foo,&foo,the fh foo, and the format foo,(I'm sure I missed something,,but don't know what.)
\*foo is a reference to the typeglob.
A typeglob or a ref to it, can be used as an "indirect filehandle".
Typeglobs are also used to create aliases:
*foo=*bar; #Now everything named bar is also named foo
*fooo=\$barr #now $fooo is an alias to $barr
And to create a refernce using the *foo{THING} thing which is explained in perlref(As the 7th way to create a reference).
For more about typeglobs, read perldata.