How to fetch (join) two records from database using doctrine/symfony4

I am learning about Symfony and Doctrine and created a simple site but I am stuck at this step.

I have two tables: users and languages

Users Contains: id, username ...
Languages Contains: user_id, language...

Here is a image of the two

Now I am trying to fetch by language, like: get user who speaks both english and french and the result would return user id 2

In plain PHP i can do inner join with PDO, but I am trying to follow the doctrine syntax and this does not return the correct result

public function getMatchingLanguages ($a, $b) {
  return $this->createQueryBuilder('u')
    ->andWhere('u.language = :val1 AND u.language = :val2')
    ->setParameter('val1', $a)
    ->setParameter('val2', $b)
    ->getQuery()
    ->execute();
}

I call this method in my controllers, and the query is pretty basic since I can not find a documentation how to do the joins as per my example

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