Looking at the new USW-Flex-2.5G-8-PoE switch and don't understand what the following means.

From the specs:

|| || |PoE interface|(8) 60W PoE++ (Pair A 1, 2+; 3, 6-) (Pair B 4, 5+; 7, 8-)|

|| || |Power method|(1) AC power adapter, 54V DC, 3.9A (Not included) (1) PoE+++ (PairA 1, 2+; 3, 6-)(PairB 4, 5+; 7, 8-)|

I understand that an AC power supply is not included.