The first picture:
Top left: start using; Bottom left: pause;
Right: When the warning sign appears, turn to the position of 0, wait for 5 seconds, and then turn to the position of 1 again.
The second picture:
Summer: Point the pointer to the (shaded) area.
Winter: Set the pointer to 1-5 to adjust the water temperature in the heating (or heating, I don't know what you are) equipment.
The third picture:
Healthy hot water temperature:
When it points to 0: the water heater stops heating;
From 1 to ECO: the water temperature is about 38 degrees to 50 degrees.
ECO: the highest temperature advocated for daily use.
Between ECO and max: over 50 degrees, use with caution.
The fourth picture:
If the pressure reading on the pressure gauge is lower than 1, open the blue valve placed under the boiler and fill the equipment with water until it reaches 1.5.