A double headed arrow simply means two electrons are being moved. So in this case, I have two electrons moving from my pi bond, and they move on to one of the orbitals on the oxygen. And now I no longer have this because these electrons have moved here. So this is, once again, this arrow signifies movement of electrons and not movement of atoms. In other words, if I draw this molecule or this compound where I took this atom and placed the atom onto one of the orbitals here, so now there's a bond, a sigma bond between oxygen, carbon. This is not a resonant form.