any word (html) you put between the single quotes will be echoed when you echo $output
.
so you can do this:
$output .= '<div class="dhvc-woo-view">View: ';
$output .= get_post_meta($post->ID, 'pageview', true);
$output .= '</div>';
or
$output .= '<div class="dhvc-woo-view">';
$output .= 'View: ';
$output .= get_post_meta($post->ID, 'pageview', true);
$output .= '</div>';
it’s the same.