Re-order product tabs

Paste the following code in your theme’s functions.php:

add_filter( 'woocommerce_product_tabs', 'woo_reorder_tabs', 98 );
function woo_reorder_tabs( $tabs ) {

  $tabs['reviews']['priority'] = 5;			// Reviews first
  $tabs['description']['priority'] = 10;			// Description second
  $tabs['additional_information']['priority'] = 15;	// Additional information third

  return $tabs;
}

Note: change the priority value depending on your needs.

Source: https://docs.woocommerce.com/document/editing-product-data-tabs/