How can I work with OOP in C++ module to be able to call by functions from GDScript?
For example: Room.get_human().get_name()
Please clarify your question, OOP is quite a wide concept.
Do you want to call C++ functions from GDScript or call GDScript functions from C++? Or something else?
I want to call C++ functions from GDScript
In Godot, any class inheriting Object (or Node, Reference etc) have access to a reflection API allowing other languages to call methods on them.
You have to implement _bind_methods() and register your class in ClassDB.
This is covered in the official documentation here http://docs.godotengine.org/en/stable/reference/object_class.html#registering-an-object
And this is an example in Godot source code: https://github.com/godotengine/godot/blob/master/scene/2d/sprite.cpp#L295