Shimano 105 disc brake lever travel question

Air in the line means the contents of the brake line should be able to be compressed. The low amount of force needed to move the brake pads to touch the rotor means that you’ll should be able to see that happen as you squeeze the brakes. On a properly bled system there won’t be much more travel left to the brake lever as the fluid won’t compress. If there is air there will still be easy ability to squeeze more as the air gets compressed