Yeah, its a messy format, but still, have you tried all suggestions below?
Something on your system prevents the installation/startup of the BE Service, which is required to play on BE-enabled servers. Please ensure that any security software (anti-virus, etc.) running on your system doesn't block the BE Service (both BEService.exe/BEService_x64.exe in your game's "BattlEye" directory as well as BEService.exe in the BE Service directory, which is usually "C:\Program Files (x86)\Common Files\BattlEye") in any way. You might have to add it to your security software's exception list. If that doesn't help or you don't use any sort of security software there might be a permission issue with your BE Service directory or the files within it. To solve this delete the BE Service directory (usually "C:\Program Files (x86)\Common Files\BattlEye") and then try to launch your game again. If you still get the same error at this point please try to manually set the BE Launcher (for ArmA 2: Operation Arrowhead: "ArmA2OA_BE.exe" in your game directory) to run with administrative privileges (normally this should happen automatically). To do so right-click on the BE Launcher executable, choose "Properties", go to the "Compatibility" tab, check the "Run this program as an administrator" option and click OK to apply your changes.