There are only 6 globs slots and they are SCALAR, ARRAY, HASH, IO, FORMAT and CODE, so I can only assume by *glob{FILEHANDLE} you mean *glob{IO}. The *glob{IO} slot holds the reference to the IO object associated with a glob's filehandle (assuming it exists) e.g 
open(FH, $0);

print "*FH IO slot holds - ", *FH{IO}, $/;

__output__

*FH IO slot holds - IO::Handle=IO(0x8107e4c)

[download]
Not meaning to plug (but will anyway) I'd recommend Of Symbol Tables and Globs for more info on globs and glob slots.
How/where/why it is used? Please give me example.
Accessing glob slots directly is very rarely done, and when it is, it's usually for doing low-level code like writing Exporter type code. Here's a simple demo of such code (if somewhat contrived) 
sub import {
  my $pkg = caller;

  ## import only filehandles
  *{"$pkg\::$_"} = *{__PACKAGE__."::$_"}{IO}
    for keys %{__PACKAGE__."::"};
}

[download]

HTH

_________
broquaint

update: s/DIR/CODE/ + added example

In reply to Re: *glob{FILEHANDLE} by broquaint
in thread *glob{FILEHANDLE} by rakesh1377

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.