The Force: the source of all power in the universe, the thing that both the Jedi and Sith claim to serve, and presumably the energy that put Rey and Finn where they needed to be at just the right time to kick start the whole shebang.
Basically, it's the best deus ex machina in the galaxy (far, far away).
May the Force Be with You
In symbolic terms, the Force is a quasi-religious concept, standing in for God, the cosmos, and whatever energy put the universe in motion. George Lucas conceived of it as a theological idea: a way to talk about God and the mysteries of creation without getting bogged down in any particular religion. Why not make God a little more tangible and use it to discuss big issues like how hard it can be to do the right thing?
Critics dismissed the idea as pop religion, and they're not entirely wrong. But that also misses the point a little bit. The point is that while the Force gives Jedi cool powers and arranges for convenient meetings that change the galaxy for the better, we don't really know any more about it than we do about God.
It's a great, big mystery, and accordingly, when characters try to follow the Force's guidelines, they can sometimes be led astray, misinterpret what it's telling them, or just generally mess things up good and proper the way we do in our own lives.
And that leads to another key point. Whether you call this power God, fate, destiny, or something else, when it taps you on the shoulder, you need to be ready to go. It's the same with the Force. It wants Rey to get into the game, even offering her Luke's lightsaber to give her a hand.
But she's not keen on it, in part because she's struggling with what it's saying to her and is more than a little afraid of the answer. Turns out it's for the best, though. The Force really does know what it's doing…even if the characters don't.
And that's a comforting thought no matter what label you choose to slap on it.