How to check if my house is properly grounded?
Based on the model of the surge protector, I'm going to guess those are German outlets.


  Does that mean my house is not properly grounded? How do I check? Is there any risk if your house is not properly grounded?


Something like a socket tester can tell you the status of an outlet These can be found at most hardware stores or online:



https://www.amazon.de/Schwabe-Steckdosen-Tester-Null-Leiter-Anschluss-Prüfstecker-Schuko/dp/B01I3IPV1I

This will tell you whether or not your outlets are properly grounded. The surge protector has a version of this tester built-in, and it's showing that the outlet you have it plugged in to is not grounded.


  The surge protector says "This product must be connected to earth ground" in the back. So is it safe to use even if my house is not properly grounded?


Without grounding, the surge protector becomes a power strip. The surge protection is designed to redirect "surges" of electricity to ground, instead of to the outlet where equipment could be harmed. So the harm is that you might think your equipment is protected when it might not be.