Only the deranged pickled brain of Putin knows

During the lead up to Feb 24th, the orcs were applied their war-markings to invasion army vehicles.

They painted big white letters. Some groups were photographed having painted a big Z. Others painted O or Ø. V was another common one, but there were other letters and markings photographed during the early invasion. Eventually the orc ur-mind selected Z as the pictorial marking for their blood war.

One common guess

Z - zapod, запад, west group, the group approaching from belarus. But actually they were photographed all over the place

Ø - center group

V - Vostok, восток, the group approaching from the east

Another guess was that Putin, ever the paranoid esotericist, was hexxing Zelensky.

V O Z - volodymyr oleksandr Zelenskyy