add_filter('manage_posts_columns', 'add_slug_col');
function add_slug_col($cols){
        $cols['slug'] = __('Slug');
        return $cols;
}
add_action('manage_posts_custom_column', 'get_slug_show');
function get_slug_show($column_name){
        if($column_name == 'slug'){
                $get_slug = basename(get_permalink(get_the_ID()));
                echo $get_slug;
        }
}