Well, for starters, fixing the obvious mistakes:

use strict;
our $it; 

my @fils;

foreach my $line (@fils) {
  if ($line =~ /aa bb cc/) {

$it = 4;

# do  something


}

if ($it == "4") {

# more stuff
}

}
[download]

Other than that, I have no clue what you are trying to do.