Colour analysis is the practice of identifying which palette of colours harmonises with your natural colouring, your skin's undertone, the depth of your hair, the contrast in your features, the warmth or coolness of your eyes. It's not opinion. It's optics.
When you wear a colour that belongs to your palette, light reflects upward onto your face and does the work of a good ring light. Skin looks more even. Shadows under the eyes soften. The features sharpen because the face, not the fabric, becomes the focal point. People will tell you that you look well-rested, that you've lost weight, that something is different, they rarely know what.
Wear the wrong colour and the same optics work against you. The fabric pulls colour out of the skin. Undertones that should stay quiet, sallowness, redness, greyness, shadows, are amplified. Features recede. You look tired in photographs you didn't feel tired in.