There is something wrong here. A German soldier holds a non-German gun. Where were such guns made?

The PPSh-41, nicknamed Pe-Pe-Sha is the Soviet submachine gun which "won the World War II". It was greatly inspired on the Suomi KP/-31 used with great effectiveness by the Finnish army in the Winter War against the Soviet Union. The PPSh-41 was brought to mass use by the Soviets during the battle of Stalingrad, where entire units armed with submachine guns outgunned their German counterparts in short range urban combat.