apply_filters ( 'jetpack_sharing_headline_html', string $sharing_headline, string $global[’sharing_label’], string $sharing )

Notes

You can use this filter to customize the HTML structure of the Sharing buttons headline. In the example below, we’ll change the Sharing buttons’ headline structure to use h1 instead of the default h3:

function jetpackcom_custom_heading( $headline, $label, $module ) {
        if ( 'sharing' == $module ) {
                $headline = sprintf(
                        '<h1>%s</h1>',
                        $label
                );
        }
        return $headline;
}
add_filter( 'jetpack_sharing_headline_html', 'jetpackcom_custom_heading', 10, 3 );