Guardians Of The Galaxy Vol 2 Teaser Breakdown: 15 Things You Must See

That's definitely either a beacon or some sort of powerful object that requires the actual guardian duties of the Guardians.

In all honesty, I would be foolish to try and hazard a guess, though we can be almost 100% certain that it's not powered by an Infinity Stone. Not only has James Gunn assured everyone who will listen that we won't see one, it's also yellow, which is limited to the Mind Stone currently plugged into Vision's forehead.

Whatever it is, it looks extremely powerful.

And we can also be pretty sure she's not defending it from her sort-of father, Thanos, because he's not turning up either according to Gunn. Whoever/whatever it is she's fighting, it's enormous and it has massive tentacles...

So there's the answer then, it's the Abilisk that was shown in the concept art and shown in the teaser footage at Comic Con...

And that suggests that the "beacon" is probably something to do with inter-dimensional travel and that this is probably the opening action set-piece.