fine having said that
the pattern can be

m/^Summary\s*\d+\(\d+\)/
[download]

use FileHandle;

$fh = new FileHandle '<input.txt';

$in_body = 0;

while (<$fh>) {
        if ($in_body) {
               
                if (m{SUMMARY.*?>}i) {
                        $in_body = 0;
                } else {
                        ($row1, $row2) = split ;
#                       print "$row1", "\t",  "$row2" , "\n";
                        print;
                }
        }
        elsif (m{/SUMMARY.*?>}i) {
                $in_body = 1;
#               print;
        }
[download]

Here i can get the data where the end is /SUMMARY. For the column data I want to convert to row data. So that i would have:

summary        col1    col2   col3 ....
SUMMARY XXXX
SUMMARY YYY
[download]

If you use parens, like m/SUMMARY\s(.*)\n/i then $1 will contain whatever matched .*
-- Time flies when you don't know what you're doing

Welcome to the Monastery, indieBoy!

Please take the time to skim the Guide to the Monastery and the PerlMonks FAQ, specifically Posting on PerlMonks, to get started. Read at least Markup in the Monastery and How do I post a question effectively?
It is good practice to post one's current attempt at solving a problem. Showing one's effort makes it more likely to get help, since The Monastery isn't a "code writing service" ;-)

That said - use a Flip-Flop:

my $pat = qr{Summary \w+\(\w\)};

while(<DATA>) {
    if (/$pat/ ... /$pat/) {
        next if /$pat/;
        print;
    }
}

__END__
gargantua
pantagruel
Summary 1000(1)
top
Date ....
Column1    Col2   Col3
bottom
Summary xxx(x)
foo
bar
baz
[download]

Output:

top
Date ....
Column1    Col2   Col3
bottom
[download]

See perlop, there binary "..."

update: added greeting