It only has an indirect display of humidity by setting the desired target humidity and when this is reached the display changes.

From the instructions "Humidity display information":
The humidifier is equipped with an integrated humidity sensor. You can set the target humidity to 40 % RH, 50 % RH and 60 % RH. When the desired humidity is reached, the humidity indicator lights up blue. When the humidity is below the set value, the humidity indicator lights up red.