A Shuttle Run: two lines 10 yards apart. You stand parallel to one line, the line should be either to your right or left. This is the tricky part, run sideways to the line, touch it, come back to the first line, touch it, then sprint to the second line. It's like when a linebacker scrapes to the outside on a run play, it's a quickness move.
Hope this helps. Try searching the web for some illustrations.
Peace.