Here's what happened:
* Fawkes arrived just in time: When Harry was facing the Basilisk in the Chamber, Fawkes appeared, seemingly out of nowhere.
* He distracted the Basilisk: Fawkes attacked the Basilisk with his powerful beak and talons, distracting it from Harry. This gave Harry a vital moment to recover and strategize.
* He healed Harry's wound: After Harry was poisoned by the Basilisk's fangs, Fawkes used his tears to heal the wound. These tears are known to have powerful restorative properties.
While Fawkes didn't defeat the Basilisk himself, his timely arrival and actions were vital to Harry's survival. He effectively saved Harry's life, allowing him to ultimately defeat the Basilisk with the Sword of Gryffindor.