What is the white calorie number below Move actual/goal calorie

On the green exercise section, which counts in 15 minute intervals, the green bars count how many minutes in that 15-minute period you were exercising. So if you exercise from 8:13 to 9:13 straight, you’ll see a two-minute bar, three 15-minute bars, and a 13-minute bar. The number you indicated will show 15, because the max rate of exercise was 15/15 minutes.

For the red move section, the number is the highest number of calories burned during one of those 15 minute periods.

And where it says Total under the exercise minutes,that is how long you have been wearing the watch that day.

A flight of stairs is counted as approximately 10 feet (3 meters) of elevation gain (approximately 16 steps),this is quoted from the health app.

where are you seeing this? A specific watch face? In an app on the watch? In a Watch app on the phone?