在这种情况下，您需要检查何时启用过滤器并采用选定的属性分类法“pa\\U brand”：

add_action( \'woocommerce_before_shop_loop\', \'desc_before\', 75 ); 

function desc_before() {
    if (is_filtered()) { 
        $brands = WC_Query::get_layered_nav_chosen_attributes() [\'pa_brand\'];
        if ( isset($brands) ) { 
            foreach ($brands[\'terms\'] as $term ) {
                $term_obj  = get_term_by(\'slug\', $term, \'pa_brand\');

                echo \'<div class="ka-attr-description">\'.
                     \'<h4>\' . $term_obj ->name . \'</h4>\'.
                     $term_obj->description.
                     \'</div>\';
            } 
        }
    }
}