The Guardians of the Galaxy are a group of powerful beings dedicated in protecting the universe from the powers of evil who seeks to conquer or destroy it.
Michael Korvac (episode)
After the Guardians introduced themselves and their reason of capturing Korvac, the Avengers decided to help them apprehend the mad-crazed cosmic being. Despite their best efforts, they were easily defeated by Michael until Corrina was able to help Korvac come to his senses which led to the latter's self-exile in the unknown reaches of cold space.
Since Korvac's gone, Iron Man wanted the Guardians to tell them everything what other threats they encountered and known in the galaxy but Star-Lord prefers not to tell them, saying: "There are things out there in the universe you're better off not knowing about".
The Guardians have presumed to have left Earth after that.