Seems you do not understand OO (Object Orientated) programming.

It seems the answer above what you circled answers your question.
I did not read all of that nor can i.. it's a screen cap.

I think English is not your fist language so find a book in your native language on OO programming.
Or get better at English

I prefer c or c++ which has tacked on limited amounts of OO crap.
C / C++ are not OO languages.
So i done coding with Csharp etc over the years but i prefer old school 'C'