Игорь Воротнёв

_n( '%s person', '%s people', $count, 'text-domain' )

<?php echo wp_kses_data( _n( '%d', '%d', WC()->cart->get_cart_contents_count() ); ?>

'meta_query' => array(
    array(
     'key' => 'color',
     'compare' => 'NOT EXISTS'
    ),
)

Summary:

If it ends with / it can never be a file. No server guessing.
Slash or no slash are entirely different meanings. There is a technical/resource difference between "slash or no slash", and you should be aware of it and use it accordingly. Just because the server most likely loads /dvd/index.htm - or loads the correct script stuff - when you say /dvd: It does it, but not because you made the right request. Which would have been /dvd/.
Omitting the slash even if you indeed mean the slashed version gives you an additional HTTP request penalty. Which is always bad (think of mobile latency) and has more weight than a "pretty URL" - especially since crawlers are not as dumb as SEOs believe or want you to believe ;)