This Salus does not have on and off. It is always "on"! Hard to get your head around, but that's the way it is.
Each 24 hours is broken up into 5 segments. When you program it, you set the time when each time slot begins and the minimum temperature you want to maintain for that time slot. The heating is off when the room temperature is above the programmed temperature, on when it goes below.
A typical program (I'll describe the factory default setting) has time slot 1 at 21C for a while in the morning, then time slot 2 at 14C during the day, then time slot 3 at 21C for a couple of hours, then time slot 4 at 21C for the rest of the evening, then time slot 5 at 14C during the night. The jumper on the back lets you control each day individually, or just have two programs for weekdays and weekends. In most cases, the setback temperature of 14C is low enough that the heating will stay off, but in winter it may kick in for a while. If you don't like this you can set it lower. If you really hate the whole idea, you may need to get a different controller.
You can manually adjust the set temperature at any time by pressing the up or down buttons. This setting will remain where you put it until the next time slot kicks in, which might be 5 minutes or the rest of the day, and then revert to the program temperature. You can switch the heating off completely by pressing and holding both the up and down buttons together (exactly together!) until the display goes off. The manual calls this sleep mode. You'll have no heat until you press a button and the display comes back on. You can reduce the set temperature to 5C 24/7 by pressing the frost button on the bottom left.