The rode is comprised of an anchor chain which is attached to the anchor (used to ballast the line) and the rope or line that attaches to the mooring buoy.
Scope is simply the length of the rode. An anchor holds best when the anchor shank is as close to horizontal as possible. The minimum recommended scope is 5 to 1 or 5 times the depth of the water. The ideal scope is a ratio of 7 to 1. By increasing the scope you can increase anchors holding power.