what's exactly meaning of "Enables overriding of any property reference with global properties"?

my intention is simple: I would like to allow a QA/Dev engineer who is going to run SOAPUI  tests to pass in some parameters as global ones when they start a test via command-line. the global variables might have same name as variables at project/test suite/test case levels,  I am just wondering what's the impact of this overriding option. I couldn't find any further detailed explanation about this flag.

Thanks,

Sizhou.