alrighty so i’ll try to explain this as best as i can - from what i gather ((i’m not an expert and i may be wrong)) the pic was taken in a room with very bad lighting ((not outside/no light from a window)) so it has a bright yellow tint. the original dress is likely a dark blue or black and a lighter blue.
soooo the lighting gives it a very bright yellow tint. if your computer/phone/etc. is calibrated to have high gamma and have warmer colors vs cooler colors, you will likely see white and gold. if your computer/phone/etc. is calibrated to have low gamma and have cooler colors vs warmer colors, you will likely see dark blue/black and a lighter blue.
like i said, i’m no expert. but you can test and calibrate your monitor here for more accurate colors. the dress is a dark blue/black, it’s more evident here.