Deset deka šunke means one hundred grams of ham. Croatian counts in decagrams here: deka is ten grams, and ten times ten grams is a hundred. The word “gram” itself is usually dropped.
In the image you eat a dessert and cover it up so it does not go cold: dessert and covering (decken in German) give you deset deka. Then you sway along to music and cut a notch into the ham – swaying (schunkeln in German) and ham give you šunke.
So if you only hear deka at the counter, it is units of ten grams – just multiply by ten.