What does the Hellsing symbol mean, the one with the pentagram, and those strange letters?

It means Nazi

As it's a pentagram in a circle surrounded by words in known language, and what could be either imaginary script or some 'language' used in ceremonial magic, I don't think Nazi comes into it. The Hellsing organisation was created to counter attacks from vampires rather than to dominate the world. Mind you, if you are one of the vampires on the wrong side, it wouldn't be your favourite organisation...

The script is reminiscent of Mxedruli (Georgian), but doesn't match up. I can't at the moment find the Abkhaz script, which is Mxedruli with extra characters, but I would think it's more likely to be an invented script. The symbols in the pentagram resemble alchemical symbols, but are also possibly invented. It's not hard to invent these things. Reference to what the Hellsing symbol looks like:


http://kurofushicho.deviantart.com/art/Alucard-s-symbol-15453248

And:

http://calmmart.deviantart.com/art/Hellsing-symbol-301881149

The only reference to Nazis on the pinnacle is the "Gott Mit Uns" on the bottom. It was what the German soldiers in World War II had on their belt buckles. But this probably has to do with how Alucard and Walter destroyed, or thought they destroyed, Millenium.
https://en.wikipedia.org/wiki/Hellsing:_The_Dawn


I don't think there is too much information on the pentagram symbol. I have heard that it keeps Alucard under control before. Which could make sense because Zorin has a similar one on her face, but I'm not sure if she's under control of The Major or anything.