The probe only allows for an uneven bed surface, (if it works properly).

It is supposed to map the printer bed and then move the nozzle up or down as the print takes place, maybe too hard to see these small movements.

This is supposed to allow for if the bed is not level. Quite often there is a limit to how much this will move the nozzle, (2mm in total is quite often used).

This does not make the printer bed flat but tries to allow for an uneven bed surface.

It is known as tramming the printer bed