This board tells a USB-C PD power supply to apply 5v to the VBUS pin by pulling CC1 and CC2 pins to ground through 2, 5.1k resistors.

Some (cheaper) devices that have a USB-C port don't have that circuitry, so they will not charge with most USB-C power supplies, and that's why they usually come with a USB-A to C adapter cable. This works because USB-A always has 5v on the VBUS pin.

So by using this board, you can now charge those devices without that stupid USB-A to C cable and get rid of USB-A power bricks and finally switch to USB-C.

It has an LED that lights up when the board has 5v on the VBUS pin letting you know that it's working and power will be available to whatever device you plug it into.

This board can be installed directly at the USB power supply, or at the end device. I recommend at the end so you can remove it easily and charge devices that can charge faster than the 5v/3A (such as iPhones, etc).