So here's the scoop. My first inclination was that it was a reflection from something behind the picture taker. So I cropped the pane of the window and zoomed, also I brought out the colors and brightness to get a clearer view.
So as you can see it is a reflection, and at first I though "Ah hah!" its light coming from between the branches of the bush being reflected. But, then when I examined it closer you can see there is a fence in the back of the reflection. And the fence is even visible from where the two faces are seen.
If you can see the faces images overlay the fence and even the branches of the reflected tree.
As a matter of fact the the image overlays the window itself. If the image was behind the window you would see the imperfections and irregularities from the reflection within the face. But we do not. Even at a great magnification the image of the face overlays everything.
So that makes me a bit suspicious. You said you took the image, did anyone have possession of it prior to you uploading it? The reason I asked is that I looked within the encoding of the image and it shows it was edited with PicNik photo editing and effects software. Do you have the original directly from the camera you can upload?
Thanks!