As you are probably aware Stalag (short for Stammlager) is the German name for an enlisted man's prisoner of war camp.
Stalag IVB was located at Mühlberg near Dresden. The number 227576 will have been allocated to a specific soldier POW in the camp, and he can probably be traced through the ICRC records.
The writing on the bank note means the following;
Reihe = rank or row
Reichsbanknote = Reich [state] bank note (I think the 'f' has been misread, and is actually a 'k')
funfzig = fifty
Mark (not marf) 50 ie the denomination of the note. 50 reichsmark was worth around £4 / 7 shillings in 1940. If the POW had been working, for instance on a farm or other non-military related occupation, this may have represented his pay