They appear to connect every element in the footprint to pin 1. They appear only when the component is selected, and only when B. Silkscreen is visible.
I’ve never seen them before, and can’t quite imagine what they’d be used for…
Ralph is right, the text locations are bind to the footprint origin, and the lines are visible only when the footprint is selected. If there weren’t those lines and text would be placed outside footprints, it would be impossible to know which text belongs to which footprint.