2 X Empty Kaffee-Konserve means coffee jam.
It is more appropriate to understand the jam-like coffee, but there is very little information on this food.
Apart for KAFFEE - KONSERVE , there are red warnings that read Zum Gebrauch bei Ermüdungscheinungen "Use only under fatigue" and the ingredients Mokka mit Kondensmilch und Traubenzucker Coffeingehalt ca. o,1g. "Mocha coffee with condensed milk and glucose, caffeine content 0.1g"
There is also a series of red letters that read "Nach Frau Anna Holsing, Bremen - Katrepel". This may be the manufacturer and the place of production.
With aluminum caps but both empty.

The last image is a known image of these products and is only a pictorial image.