It's an ad, but it includes a description on how the cooker is used.
previously I thought its from kocher box but ad makes more sense
Here is a full translation:
The soldier's cooker
How to use Esbit
the fuel in tablet form?
With the Esbit cooker no. 9, the fireplace is ready to use after opening the side panels. Place one or two Esbit fuel tablets on the flat tablet tray in the center and ignite them with a match. The cooking vessel - which should be thin-walled if possible - or the opened can of food is placed on top of the vertical side panels. If small cooking vessels such as drinking cups are used, it is sufficient to open the cookers' lateral panels to the first notch. Then, the cup is resting on the slanting side panels.
[Illustration with captions 'closed' - 'half opened' - 'fully opened'*]
Esbit fuel can be added, blown out and re-ignited later without any danger.
Esbit is used:
to heat food and drink, especially canned food;
to heat water for shaving, rinsing the mouth and teethbrushing;
to make tea, broth, grog;
to prepare warm sausages, fried eggs, fried potatoes etc.
Esbit dry fuel is available in packs of 10, 20, 50 and 100 tablets from pertinent retailers.
Where it is unavailable, sources of supply are provided by the exclusive manufacturer:
Erich Schumm, Esbit Fuel Factory, Stuttgart-W., Reinsburgstraße 96
*) Hasn't changed that much since: