Hi hasse,
It is against the rules of this forum to promote specific services or businesses but if you google "germany+property" or "german+real estate", you should be able to find various sources on German real estate, including brokers in Germany that provide services in English.
The amount of information and offerings may, however, be overwhelming. You should therefore first have at least some idea where you want to invest, how much you want to invest and what kind of strategy you would like to pursue (immediate return, capital appreciation, inflation protection etc.). Don't get too focused on a specific type of property; depending on what you want to achieve, you may be better off buying 2-3 high quality apartments rather than a whole apartment block with 20 apartments.
For people starting out on their research on the German real estate market, I usually recommend the
Deutsche Bank Research - German Residential Report, which is available for free and in English language.
I will quite gladly try to answer any further questions you may have in this forum, or please feel free to contact me by PM.
Good Luck!