Seems like most airports have them now, you print out your own luggage tags. Someone was there to help but then you place it on the belt and it weighs the luggage. If it’s over the 23kg limit for regular checked luggage it won’t “accept” the luggage and you’ll need to make it lighter or pay the heavy luggage fee.
But if you are priority or whatever the weight limit is higher but their system doesn’t recognize that, so the lady had to take the bag to the special assistance line.