What does NA+ROW mean?

"Rest of World (ROW)" really just means 'all parts of the world we don't have special restricted versions for'. "World Wide (WW)" is actually the one that means "activatable anywhere", though ROW is generally used to mean the same thing, where region-restricted versions of a game don't exist.

Looking at SteamDB, Germany and Australia seem to have region-specific versions (which is normal, as both regions are notorious for their game censorship).

As far as the NA+ROW version, here are the regions which SteamDB lists as not having access to it:

Albania, Andorra, Austria, Belgium, Bosnia and Herzegovina, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Georgia, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Liechtenstein, Lithuania, Luxembourg, Macedonia, Malta, Monaco, CS, Netherlands, Norway, Poland, Portugal, Romania, San Marino, CS, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey, Great Britain, Holy See (Vatican City State), Aland Islands, Faroe Islands, Gibraltar, Guernsey, Isle of Man, Jersey, Svalbard and Jan Mayen,

Looking at the list above, I assume the EU version of the game is also region-locked. There's also an Asian version, a Japan version, and an RU+CIS version, but it looks like those regions (as well as Australia) can still activate the NA+ROW copy.

Follwing the region lock of Deep Silver bundles, it seems likely that the key will not work in Germany.