Hello nursyza, and welcome to the Monastery!

Parentheses within a regex are for capturing a match. To match a literal left parenthesis, you have to escape it:

use strict;
use warnings;

my $MODULE_NAME = 'MODULE C17 (N1, N2, N3, N6, N7, N22, N23)';

if (defined($MODULE_NAME) && ($MODULE_NAME =~ / ^ (.+) \s+ \( /x))  
{  
    my $module_name = $1;
    print "Module name = >$module_name<\n";  
}
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Output:

18:49 >perl 1939_SoPW.pl
Module name = >MODULE C17<

18:49 >
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Note: The /x modifier is used here to make the regex more readable. The regex says: match the beginning of a line (^), then capture as many characters as possible, providing that these captured characters are followed by (a) one or more spaces, then (b) an opening (left) parenthesis.

Update: My use of \s+ above is sub-optimal, because it matches only the last whitespace character following the module name. Better would be:

if (defined($MODULE_NAME) && ($MODULE_NAME =~ / ^ (.+) \( /x))  
{  
    my $module_name =  $1;
       $module_name =~ s/ \s+ $ //x;
    print "Module name = >$module_name<\n";  
}
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which explicitly removes trailing whitespace from the module name.

Hope that helps,