This instrument displays an odometer and two trip meters.
The odometer shows the total distance traveled by the vehicle.
The two trip meters show two different distances traveled independently since each meter was last reset to zero. You can use one trip meter to calculate fuel economy and the other to measure the distance for each trip. If the power source is disconnected, all trip meter data will be cleared.
The trip counter reset button allows you to reset the two trip counters to zero, as well as change the trip counter readings.
The text is quoted from the source website: ToyotaMan.ru
To change the meter reading, quickly press and release the button. The meter reading will change in order from odometer to tripmeter A, tripmeter B, then back to odometer each time the button is pressed.
To reset the A meter reading to zero, first display the A meter reading, then press and hold the button until the meter reaches zero. The same procedure can be used to reset the B meter reading.