The NRF52840-PDK is a versatile single board development kit from Nordic Semiconductor which is designed for Bluetooth 5, Bluetooth low energy, ANT, 802.15.4 and 2.4 GHz proprietary applications using the nRF52840 SoC. This kit supports development for the nRF52840 SoC. It is also hardware compatible with the Arduino Uno Revision 3 standard, making it possible to use 3rd-party shields that are compatible to this standard. The kit gives access to all I/O and interface via connectors in addition to four LEDs and four buttons that are user-programmable. Adding an NFC antenna allows the kit to enable NFC tag functionality.
One application where you can use the NFC Antenna is your smart phone. Once NFC is turned on it can connect in seconds! I used my phone to connect to the device, which brings you to the startup page for the development kit. From there I downloaded the nRF Toolbox App and had the ability to use 7 different sensor applications. Once in the app it uses Bluetooth low energy which also works with a wide range of BLE accessories such as Fitbits®. You can download the app on iOS, Android, or Windows Phone platforms.
You can find more in depth information on the EEWiki page. If you have any other questions I will be able to answer them for you on the TechForum.