The E in VE Day stands for Europe.
VE Day means Victory In Europe Day.
The Victory in Europe Day which is also commonly known as VE Day or V-E Day, is a day celebrating the formal acceptance by the Allies of World War II of Nazi Germany's unconditional surrender of its armed forces on 8 May 1945.
So when you're celebrating VE Day you're celebrating the Victory in Europe Day.
It can be a good celebration for many people who do celebrate it.