It means that Russia will insist on payment in Rubles, so the customers will have to buy Rubles,, Russia won't accept Dollars in exchange for Rubles, they will likely ask for Gold. It has the potential to screw up, then destroy currencies, especially the Euro and maybe the Dollar.

It's a game changer, Russia with potentiallly Saudi Arabia, India and China all on board, means the end of the federal reserve and it's system.

Putin used the same tactics that created then supported the Petro-Dollar's promises, made over many many years.