That is the Marshaller Distance Readout.
-0.0 0.0 was a great parking job.
The 1st number is distance from the stop point. I believe a negative means you stopped too early, and a positive number means you went too far. I might have that backwards. The 2nd number is the deviation left(-) or right(+) of the center line (assuming that the parking spot itself aligns with the actual line on the ramp).