Hello, Is any here good with c++? Please if you can explain what does this mean
double Student::GetGrade() const
It looks like the beginning of a class member function definition, which takes no parameters, returns a double, and whose "this" is const.
Most of the active programming forums, Stackoverflow especially, expect us to explain what we have already tried. So for example when I search for "c++ function syntax" I get Declaring functions - cppreference.com. That tells me that it is a "const/volatile qualification" so if I search for "c++ function const/volatile qualification" then I get cv (const and volatile) type qualifiers - cppreference.com. If you need help with that then that is what you should ask about, or at least include some of that in your question to indicate what you have tried.