Changing the WooCommerce coupon text in cart and checkout pages

Want to change the WooCommerce coupon text… there are a few areas that need to be tackled namely the cart and the checkout pages, WooCommerce has most of the filters needed and the gettext filter can finish off translating the text string.

add_filter( 'gettext', 'bt_rename_coupon_field_on_cart', 10, 3 );
add_filter( 'woocommerce_coupon_error', 'bt_rename_coupon_label', 10, 3 );
add_filter( 'woocommerce_coupon_message', 'bt_rename_coupon_label', 10, 3 );
add_filter( 'woocommerce_cart_totals_coupon_label', 'bt_rename_coupon_label',10, 1 );
add_filter( 'woocommerce_checkout_coupon_message', 'bt_rename_coupon_message_on_checkout' );
/**
 * WooCommerce
 * Change Coupon Text
 * @param string $text
 * @return string
 * @link https://gist.github.com/maxrice/8551024
 */

function bt_rename_coupon_field_on_cart( $translated_text, $text, $text_domain ) {
	// bail if not modifying frontend woocommerce text
	if ( is_admin() || 'woocommerce' !== $text_domain ) {
		return $translated_text;
	}
	if ( 'Coupon:' === $text ) {
		$translated_text = 'Voucher Code:';
	}

	if ('Coupon has been removed.' === $text){
		$translated_text = 'Voucher code has been removed.';
	}

	if ( 'Apply coupon' === $text ) {
		$translated_text = 'Apply Voucher';
	}

	if ( 'Coupon code' === $text ) {
		$translated_text = 'Voucher Code';
	
	} 

	return $translated_text;
}


// Rename the "Have a Coupon?" message on the checkout page
function bt_rename_coupon_message_on_checkout() {
	return 'Have a coupon code?' . ' ' . __( 'Click here to enter your code', 'woocommerce' ) . '';
}


function bt_rename_coupon_label( $err, $err_code=null, $something=null ){
	$err = str_ireplace("Coupon","Voucher Code ",$err);
	return $err;
}

Add the above in functions.php the example changes ‘coupon’ for ‘voucher’.

ref