Big word
I think of it as "thinking about thinking", or better yet, "learning about learning". The following link to the blog sonicbirds puts it well.
Geared to adult learners, it makes some good points on the advantages of the adult learning methodology versus kid's. Basically adults can be intentional. Please have a click below.
http://blog.sonicbids.com/how-to-learn-an-instrument-using-metacognition#.VxaIh4DwNGo.twitter
Cheers,
David Story