Show “Out of Stock” text , beside variation in Woocommerce

Add this code in function.php file:

// Function that will check the stock status and display the corresponding additional text
function get_stock_status_text($product, $name, $term_slug)
{
    foreach ($product->get_available_variations() as $variation) {
        if ($variation['attributes'][$name] == $term_slug) {
            $stock = $variation['is_in_stock'];
            break;
        }
    }
    return $stock == 1 ? ' - (In Stock)' : ' - (Out of Stock)';
}

// The hooked function that will add the stock status to the dropdown options elements.
add_filter('woocommerce_dropdown_variation_attribute_options_html', 'show_stock_status_in_dropdown', 10, 2);
function show_stock_status_in_dropdown($html, $args)
{
    // Only if there is a unique variation attribute (one dropdown)
    if (sizeof($args['product']->get_variation_attributes()) == 1) :

        $options               = $args['options'];
        $product               = $args['product'];
        $attribute             = $args['attribute']; // The product attribute taxonomy
        $name                  = $args['name'] ? $args['name'] : 'attribute_' . sanitize_title($attribute);
        $id                    = $args['id'] ? $args['id'] : sanitize_title($attribute);
        $class                 = $args['class'];
        $show_option_none      = $args['show_option_none'] ? true : false;
        $show_option_none_text = $args['show_option_none'] ? $args['show_option_none'] : __('Choose an option', 'woocommerce');

        if (empty($options) && !empty($product) && !empty($attribute)) {
            $attributes = $product->get_variation_attributes();
            $options    = $attributes[$attribute];
        }

        $html = '<select id="' . esc_attr($id) . '" class="' . esc_attr($class) . '" name="' . esc_attr($name) . '" data-attribute_name="attribute_' . esc_attr(sanitize_title($attribute)) . '" data-show_option_none="' . ($show_option_none ? 'yes' : 'no') . '">';
        $html .= '<option value="">' . esc_html($show_option_none_text) . '</option>';

        if (!empty($options)) {
            if ($product && taxonomy_exists($attribute)) {
                $terms = wc_get_product_terms($product->get_id(), $attribute, array('fields' => 'all'));

                foreach ($terms as $term) {
                    if (in_array($term->slug, $options)) {
                        // HERE Added the function to get the text status
                        $stock_status = get_stock_status_text($product, $name, $term->slug);
                        $html .= '<option value="' . esc_attr($term->slug) . '" ' . selected(sanitize_title($args['selected']), $term->slug, false) . '>' . esc_html(apply_filters('woocommerce_variation_option_name', $term->name) . $stock_status) . '</option>';
                    }
                }
            } else {
                foreach ($options as $option) {
                    $selected = sanitize_title($args['selected']) === $args['selected'] ? selected($args['selected'], sanitize_title($option), false) : selected($args['selected'], $option, false);
                    // HERE Added the function to get the text status
                    $stock_status = get_the_stock_status($product, $name, $option);
                    $html .= '<option value="' . esc_attr($option) . '" ' . $selected . '>' . esc_html(apply_filters('woocommerce_variation_option_name', $option) . $stock_status) . '</option>';
                }
            }
        }
        $html .= '</select>';

    endif;

    return $html;
}