They are not a switch. They do nothing with the data. You still need a switch port to connect each power port to.
For each powered port they have an in and out socket.
in = data only to connect to the switch or router.
out = power and data to connect to IP phone or other Poe device.
When you are using the 8,16 or 24 port version you would usually need a set of short patch cables to connect all the in ports to the switch.
So why not just buy a POE switch?
1) Size. The spans aren’t very deep so will fit in most networking cabinets. Many POE switches are full depth devices
2) to power an existing switch. If you have made an investment in switches, you can add power without throwing away. For many high end managed switches, separate power can be cheaper than a powered switch to the same specification.
3) if you just want to power some ports.