^^&&^^

Edit File: sale-flash.php

<?php

/**

* Single Product Sale Flash

* This template can be overridden by copying it to yourtheme/woocommerce/single-product/sale-flash.php.

* HOWEVER, on occasion WooCommerce will need to update template files and you

* (the theme developer) will need to copy the new files to your theme to

* maintain compatibility. We try to do this as little as possible, but it does

* happen. When this occurs the version of the template file will be bumped and

* the readme will list any important changes.

* @see         https://docs.woocommerce.com/document/template-structure/

* @package     WooCommerce\Templates

* @version     1.6.4

if ( ! defined( 'ABSPATH' ) ) {

exit; // Exit if accessed directly

}

global $post, $product;

<?php if ( $product->is_on_sale() ) : ?>

<?php echo apply_filters( 'woocommerce_sale_flash', '<span class="onsale">' . esc_html__( 'Sale!', 'woocommerce' ) . '</span>', $post, $product ); ?>

<?php

endif;

/* Omit closing PHP tag at the end of PHP files to avoid "headers already sent" issues. */