As long as you understand what mutators and accessors are, I think you understand where they apply. They are not complicated things and their applications are very limited. In fact, it is quite rare. Unless someone comes along and tries to expand the definition of what accessors and mutators are.... Point is, you will not be writing them often.
It's just something that you learn early on because it is easy.
Rather than printing like cout << object; you first learn cout << object.getX(); Rather than doing input like cin >> object; you first learn to do cin >> foo; object.setX(foo);
Graduate from that stage and soon you are solving the same problems only differently.