You only create one $label outside of the loop. If you want to create five labels, you need to put the label creation into the loop:

...

my $vbox1=Gtk2::VBox->new;
for my $num (1 .. 5){
    my $label=Gtk2::Label->new("Total Count: $num");
    $vbox1->add($label);
}

$window->add($vbox1);
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