[IBM]

The statement is 'If all p orbitals are half filled, then there are 3 equivalent electrons (one in each p orbital, and all with the same spin, let's say it's "up"). If all the p orbitals are filled then there are two sets of 3 equivalent electrons (the three "up" electrons can exchange, and the three "down" electrons can exchange.)''
Source:https://www.thenakedscientists.com/forum/index.php?topic=74745.0 the thread title 'Why are the half-filled and fully filled orbitals more stable?
My question is that 'What do you mean by 'there are two sets of 3 equivalent electrons? As I know there are three sets of electrons in p orbitals. Could you let me clarify it, please?

[chenbeier]

In the given link its clearly explained. The electrons with same spin can be exchanged easily. Different spin need energy to change to the same spin.

[IBM]

In the given link its clearly explained. The electrons with same spin can be exchanged easily. Different spin need energy to change to the same spin.

Still, I am unable to understand. Could you simplify the point with a diagram please so that I can understand easily?