C++ code explanation request

Hello C++ experts!

Kindly explain this code in detail:

Class Queue {

Public:

Queue();

Queue(const Queue&);

Virtual Queue();

Virtual Queue& operator=(const Queue&);

Virtual int operator==(const Queue&) const;

Int operator!=(const Queue&) const;

Virtual void clear();

Virtual void append(const void*)

Virtual void pop();

Virtual void remove(int at);

Virtual int length() const;

Virtual int isEmpty() const;

Virtual const void* front() const;

Virtual int location(const void*);

Protected:

……

};