I believe exposure refers to the over exposure of the flair and the under exposure of the surrounding areas. The effect is blinding in that the image becomes hard to see and difficult to look at. This may actually match the experience and for that reason make it a valuable image in its own right but most likely not as a stock image.
the images accepted have to be technically perfect. Having blown whites and oversaturated blacks would not qualify. In addition, there are areas of lens flare as already mentioned. Here's a little rhyme for you:
Want a basic rule of thumb?
Never shoot into the sun.
The foreground is not in focus either. If you're into landscape photography, read up on hyperfocal distance.
I think the out of focus also helps match the actual experience of staring into a flare, like trying to read with eyes dilated. Not good for anyone (maybe an optometrist) commercially but has possibilities in a series on the art side.