class TestLanguage extends MY_Controller
{
    public function __construct() {
        parent::__construct();
        $this->lang->load("menu","english");
    }

    function index() {
        $data['shipping'] = $this->lang->line('menu_shipping');
        $this->load->view('templates/navigation', $data);
    }
}

class TestLanguage extends MY_Controller
{
    public function __construct() {
        parent::__construct();
        $this->lang->load("menu","english");
    }

    function index() {
        $data['shipping'] = $this->lang->line('menu_shipping');
        $this->load->view('templates/navigation', $data);
    }
}

<?php
print_r($shipping);
?>