Can someone explain exactly what this means? Is it something you need an experienced body man to do?

TIA, Kevin

They are referring to the "lip" and the wheel arch of the wheel opening. If your car is not a bondo buggy, feal under that arch and there is a ledge there... people sometimes roll, or trim that lip for clearance.

I actually used a wooden baseball bat on mine.Slide the bat between the tire and lip of fender(starting with small taper area of bat first) and roll it back and forth,gradually moving the bat up or down so that the increase taper of the bat keeps pressure on the lip as it begins to roll up under the fender.Worked great for me.

If you have a car that is a true classic and it gets judged in shows etc., than you would not want to trim the fender lip. You would roll it for your tire clearance and than you would be able to unroll that lip back in place if you where serious about your classic being judged in shows for originality. I trimmed mine....