Put this in functions.php
of your theme.
add_shortcode( 'dansk_url', 'dansk_url' );
function dansk_url() {
$output="";
$the_url= get_post_meta( get_the_ID(), 'dansk_url', true );
if ( $the_url) $output .= '<a href="' . esc_url( $the_url) . '">Dansk</a>';
return $output;
}
and use shortcode [dansk_url]
in the post.