A selvedge edge is an extra stitch at each edge of the scarf. It makes a nice even edge, and it's not counted in with the stitches. On the last scarf I did, I slipped the first stitch and knit the last stitch and it gave it a nice finished-looking edge.
Salieri, it may have been spelled that way on the pattern...I probably spelled it phonetically. Maybe Ill start pronouncing it that way, too...it'll make me sounds FANCY.