The name USB PD stands for USB-C Power Delivery. The C-type connector has a reversible tip which means there is no right-side-up orientation, which means you can plug it in without having to figure out which direction it plugs in.
The new standard provides a new variety of power voltage and amperage. One charger can provide different voltages and amperages based on any given device’s need. This frees the user from having to buy lots of different adapters.