The gist is that the picture was taken under a yellow tinted light, and your brain can interpret that as white and gold under a blue tinted light.
The dress is a photograph that became a viral phenomenon on the Internet in 2015. Viewers of the image disagreed on whether the dress depicted was coloured black and blue, or white and gold. The phenomenon revealed differences in human colour perception, which have been the subject of ongoing...
https://en.wikipedia.org/wiki/The_dress