Does your cupcake have chocolate icing on top, plus chocolate sprinkles AND a swirl of white chocolate? If so, that swirl of white chocolate is considered an embellishment — an unnecessary decorative detail designed purely to attract you. Also, can we have a bite?
Anything can have an embellishment, not just a cupcake; a building can have an unnecessary decorative element, and so can an explanation or a story. There is often a sense of deception implied by the word: it may be a harmless swirl of white chocolate but it can also be a detail designed to fool someone. Real estate agents are experts at adding embellishments to their descriptions of properties that may not be entirely true. Watch out for embellishments.