The nRF only mode disconnects the power supply of the interface MCU, the external memory, and the LEDs. It also disconnects the signal lines between the nRF52840 System on Chip (SoC) and the interface MCU using analog switches.
This isolates the chip on the Development Kit (DK) as much as possible, and can be of use when measuring currents on low-power applications.
Figure 1. nRF only switch (SW6)
