When you are in C++ you can specify a function call as BlueprintCallable using the UE4 Macro. Example - UFUNCTION(BlueprintCallable). With that you will be able to call the function from a blueprint. There are other key words to give you more functionality. I would suggest reading some of the documentation on UFUNCTION. There are also some good tutorials on writing some code in C++ then using them in blueprints. I would checkout Unreal on youtube, some of the stuff is a little dated for C++ but still works just the same when working with both blueprints and C++.
I may have misunderstood. If you are thinking that you can take a blueprint to C++ and show that things are calling the proper functions, you may want to read the documentation or How to convert a BP/Content to C++ maybe helpfull