When i am going through some code in my project, i found something term called $SIG{HUP},$SIG{TERM}. Can anybody give me some idea about these signals..

Well, here it's clear you have to do with a hash called %SIG. Check perldoc perlvar:

%SIG
$SIG{expr}
        The hash %SIG contains signal handlers for signals.  For exam-
        ple:
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and read the docs referenced therein, e.g. perldoc perlipc.

and also what are the various signals that are present in perl. I am using perl version 5.00_03.

Signals are not stuff "present in perl". They rather have to do with the OS, although (from the same source as above):

        Certain internal hooks can be also set using the %SIG hash.
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In any case if you're really interested, you may benefit from reading a UNIX programming book, even if not a Perl one.