Sample controller from Symfony docs (https://symfony.com/doc/current/routing.html)

BlogController.php

<?php

// src/Controller/BlogController.php
namespace App\Controller;

use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\Routing\Attribute\Route;

class BlogController extends AbstractController
{
    #[Route('/blog', name: 'blog_list')]
    public function list(): Response
    {
        // ...
    }
}