? mean in laravel route parameter code example

Example 1: named route with parameter laravel

Route::get('/menu/{category}/{product}/{item}', ['as' => 'named.route' , 'uses' => 'MenuController@listItem']);

// to get the actual linke
route('named.route', ['category' => $category->id, 'product' => $product->id, 'item' => $item->id]);

Example 2: route parameter type laravel

Route::get('/user/{name}', function ($name) {
    //
})->where('name', '[A-Za-z]+');

Route::get('/user/{id}', function ($id) {
    //
})->where('id', '[0-9]+');

Route::get('/user/{id}/{name}', function ($id, $name) {
    //
})->where(['id' => '[0-9]+', 'name' => '[a-z]+']);

reference : https://laravel.com/docs/8.x/routing#parameters-regular-expression-constraints