The water meter indicates water consumption in m3. There are two types of water meters: the "volume" meter and the "speed" meter.
"Volume" meter :
You will need to note down the figures on the black background, which are the ones which represent the meter reading. The red figures do not count towards your meter reading as they correspond to units of less than one meter cubed.
"Speed" meter :
You will need to take a reading of the figures in the display on the left of the "m3" unit.