Summary of the story: When Shepard calls in the Quarian fleet to destroy the Reaper, they destroy it with maximum firepower. Once the Reaper is destroyed, the Geth want to upload a code that would make their units invincible and they would then destroy the entire Quarian fleet. Unfortunately your Paragon points were not high enough to avoid this, so I decided to stop the Geth and save the Quarian fleet. Tali killed Legion shorty thereafter. Now, you have the full might of the Quarian fleet to help you.
If I had saved the Geth instead of the Quarians, Tali would eventually kill herself and the Geth fleet would help you instead of the Quarians.
After returning to the Normandy, Commander Shepard is contacted by the Asari Councilor to return to the Citadel.