I'm a computer software guy and I don't know much about electronics.
I need to buy a network switch for my children's school where I
volunteer as a network admin.

I found one on Ebay that meets my needs, except it says that it is the
"48V DC" version of the switch. The manufacturer of this switch sells it as
two different models, and this one is the "48V DC" version.

What does that mean? Am I going to need to get something else to get
power to it?