There are numerous ways you can do it.
Pass it as a parameter. - https://support.smartbear.com/testcomplete/docs/testing-with/parameterizing/script-routines.html
Use a Python Global variable. - http://stackoverflow.com/questions/423379/using-global-variables-in-a-function-other-than-the-one-that-created-them (Be careful if you use Python globals. If you don't make it obvious something is a global variable, it can get VERY confusing for someone trying to debug or alter your code in future. I also don't know how Python Globals behave between TC script units)
Use a project level TC variable. - https://support.smartbear.com/testcomplete/docs/testing-with/variables/collections/project-and-project-suite/index.html
Use a temp file. Python provides this natively as well normally, but again, not sure about within TC. - https://docs.python.org/2/library/tempfile.html
karthick7 USEUNIT I don't think is supported for Python in TestComplete. You need to use import <unit> * or from <unit> import.
If you do import <unit> * or from <unit> import * and you declare your variables globally in the unit, you should be able to get to your variables directly. Again, as with the other thread you started, reference https://support.smartbear.com/testcomplete/docs/scripting/calling-routines/declared-in-another-unit/python.html
