Fly Line Leaders show “Pounds” (LBs) on the package, what does that mean?

“Pounds” or “Lbs” refers to the breaking strength of the line. A line rated at 6 Lbs should not break until 6 pounds of pressure is on the line. You can catch fish larger than the “pounds” of you line. How? Set the drag on the reel to let the fish pull the line off the reel. That’s why you need Cortland Micron fly line backing on your reel.