The Nokia 6 comes with a rear-facing dual-tone flash, sometimes called also 2-tone, bi-color LED array or True-tone flash (as dubbed by Apple, first introduced in the Apple iPhone 5S). Those flashes use two LEDs, one with one LED that emits a warmer color temperature (amber color) and is used to help to produce an image that looks less flat and cold, depends on which lighting conditions the image was shot. The camera uses the white balance information to determine how to utilize the dual-tone flash to produce the best illumination for the specific scene the image was shot in.
You probably noticed that with a single LED flash, many of your images that was shoot indoors using the flash look "cold" and lacks the natural look. With a dual-tone flash, you'll get much more natural looking images that don't look artificial, "cold" or with unbalanced and unnatural color reproduction. Furthermore, the illumination will look much less harsh compared to a single-LED flash, more even and looks like it is spread more evenly, but that's because it produces a light that results in a more natural looking image.
It's also worth mentioning that the dual-tone flashes also helps producing more natural skin colors, more accurate flesh tones. Each of the LED flash intensity can be controlled individually by the camera, so this is how this type of flash can produce natural photos in various lighting conditions.
Just keep in mind that mobile camera flashes are still pretty weak and have limited distance coverage. This is why professional photographers shoot with a powerful external flash and not the built-in one. The built-in flash is used for front illumination and can't be projected in order directions, mainly because it is not powerful enough to be projected onto a surface like the ceiling and result in strong illumination of the scene. It would have been nice however to have a stronger flash with a rotated head that can be used to bounce (reflect) lighting from a wall and produce a more diffused lighting which results in a softer lighting. Who knows, maybe we get to see this in high-end Nokia phones someday.
Here is an excellent video by Peter C YouTube user the perfectly explains how True color Dual LED flash work with some really nice sample shot examples. I highly recommend watching it allowed me to better understand how this technology actually works.
So all in all, a dual tone flash is a nice feature that can give you more natural looking images when shooting in low-light under artificial lighting and the result is images with better color balance and more natural-looking skin tones.