It's a real color (as real as colors can be, which is not very). It's not a spectral color, you won't find it on the rainbow. It's actually the result of your red and blue cones being activated together.

so this is based off my memory so there could be inaccuracies.
but what i've heard is that pink is the result of your brain registering a color because of specific color cones being activated but that your brain knows it's not actually that color and so it fills it in with pink.

And so is brown.

Pink is actually GREEN!