Jetpack – plugin WP

function jetpackme_related_posts_headline( $headline ) {
$headline = sprintf(
            '<h4 class="jp-relatedposts-headline">%s</h3>',
            esc_html( 'Quizá también te interese:' )
            );
return $headline;
}
add_filter( 'jetpack_relatedposts_filter_headline', 'jetpackme_related_posts_headline' );