Guardians of the Galaxy (retroactively referred to as Guardians of the
Galaxy Vol. 1) is a 2014 American superhero film based on the
Marvel Comics superhero team of the same name, produced by Marvel
Studios and distributed by Walt Disney Studios Motion Pictures. It is
the tenth film in the Marvel Cinematic Universe (MCU). Part 2 was released in 2017.
So my question is, which galaxy does the film's name "Guardians of the Galaxy" refer to?
This is a bit of a trick question. See, the first movie took place partially on Xandar, which is said (in the comics) to be in the Andromeda galaxy. The second movie takes place mostly in the Black Galaxy, as that is where Ego exists (again, according to the comics). Lastly, they help The Avengers battle Thanos in Infinity War, which takes place on Earth in the Milky Way Galaxy.
So, the Guardians of the Galaxy actually help protect whichever galaxy they happen to be in at that time.