The "Live adjust Z" is a feature available on all Original Prusa printers based on the FFF technology, designed to further fine-tune (adjust) the distance between the tip of the nozzle and the print surface. By moving the nozzle closer or further away from the print surface, you can control, how much the melted filament is "squished" into the print surface and therefore affect the adhesion.
If the nozzle is too high, the filament won´t stick properly to the surface, if the nozzle is too low, the filament won´t be able to optimally "flow", leading to a potential clog of the nozzle. To learn more about this feature, please see Live adjust Z.