Hello There,
Thanks for writing in!
Because this requires a template change, I’d advise that you setup a child theme. This allows you to make code changes that won’t be overwritten when an X update is released.
Add following code into child theme function.php file:
add_filter('woocommerce_sale_flash', 'woocommerce_custom_sale_text', 10, 3);
function woocommerce_custom_sale_text($text, $post, $_product)
{
return '<span class="onsale">Sale</span>';
}
Let us know how it goes.
Thanks.