What is a point-of-load converter?
I'm using 5V as an example below.

You can either "bus around" a big 5V power system to various loads and devices using heavy duty copper wires or PCB tracks or, you can have a bunch of smaller regulators individually close to their respective loads/devices.

The latter is called a point of load converter. "Converter" is just another name for a voltage regulator and, quite often, they are switching converters. You still have to "bus around" power to the converters but this is done at a much higher voltage (maybe 48 volts) and therefore the overall current drawn in this new bus is much lower and wires/tracks can be thinner.

The other advantage is that the 48V can be quite ripply/flaky but the localized converters will turn this into a much cleaner 5V for their immediate loads.

Because lower currents now flow around the bus, emissions (EMI) are usually smaller and susceptibility (again to do with EMC) is usually improved.