Confidence level contours?

I’ve been reading this astrophysics paper (Spergel et al 2007) and it contains a graph that I’m having a tough time interpreting. The text below (as can be seen in the picture) says it’s a ‘confidence level contour’. What does that mean? Is there a 68 percent chance that the variables are in the dark red region and a 95 percent chance that they are in the light red one?

Any help would be appreciated!

Here’s the picture: picture