WordPress at a glance
action is not described

woocommerce_shortcode_before_(type)_loop action-hook . WC 1.0

Usage

add_action( 'woocommerce_shortcode_before_(type)_loop', 'action_function_name_5463' );
function action_function_name_5463( $attributes ){
	// action...
}
$attributes
-

Where the hook is called

WC_Shortcode_Products::product_loop()
woocommerce_shortcode_before_(type)_loop
woocommerce/includes/shortcodes/class-wc-shortcode-products.php 642
do_action( "woocommerce_shortcode_before_{$this->type}_loop", $this->attributes );

Where in WP core the hook is used WooCommerce

woocommerce/includes/wc-template-hooks.php 304
add_action( 'woocommerce_shortcode_before_product_cat_loop', 'woocommerce_output_all_notices', 10 );