You are correct in that the WF8F Airflo Velocity is an 8 weight line.
Here's a quick break down of how to tell what a line is by the code. The first two letters always refer to style/taper of the fly line. In the case of WF it refers to Weight Forward. This means the bulk of the weight in the line that is used to cast the rod is in the front 30-40' of line. Weigt forward lines are the standard these days. Another taper that is sometimes still used today is the DT or double Taper. This style line was designed so that both ends of the fly line are identical. With this, anglers would use one side and when it wore out, they would simple take of the line and respool reverse and use the opposite side. Double Jeopardy if you will.
The number that follows the first two letters refers to the line weight. It is this number that we use to match up with the rod weight.
The last letter, letters or sometimes number mixed with letters refers to the type of line. For example the F stands floating, meaning that the whole line floats. S stands for sinking, F/S stands for floating with a sinking tip, etc...
Hopefully this will help resolve some of the confusion that can be fly fishing.