FD not for shifting gears?
They very likely were talking about your front shifter's trim stops.
Your shifter has 3 or 4 positions despite there only being two chainrings. As you shift around in back, the angle that the chain enters the front derailleur changes. This can cause rub. The trim stops exist to change the front derailleur's position enough to eliminate the rub. In other words, when the system is set up correctly, you've got one or two stops in it that shouldn't be moving the chain. (Almost every STI now has 4 but I'm blanking on whether Claris is 3 or 4.)