Understanding reading values on electric bill

On my “readings history” I see three values in kWh, “Empty”, “Peak”, and “Full”. I am guessing that “Peak” is consumption during peak hours since the previous reading, but I cannot guess what “empty” and “full” are - though all three of these numbers correspond roughly to three different values that cycle through the display on my electric meter. Can you explain in more detail? In particular, when my bill arrives, how is it derived based on these three numbers? Thank you.