Party suit
The Spanish term 'traje de fiesta' translates to 'party suit' in English. It refers to a suit or outfit that one would wear for formal or celebratory occasions. These may be elaborate and decorated, or simply more elegant and refined than casual or day-to-day clothes. 'Traje de fiesta' can refer to a full suit, including a jacket and trousers, for men, or a fancy dress or outfit for women. The specifics may vary based on local culture and personal style.
The party dress that Marina wore was incredibly elegant.
This sentence describes a party dress worn by a woman named Marina. It's suggested that the dress was very stylish, which is demonstrated by the adjective 'elegante'.
My mother is sewing a party dress for my younger sister.
The speaker is telling us that their mother is making a party dress. It's intended as a gift for the speaker's younger sister. The action of sewing is in progress.
Please hang that party dress up after you try it on.
In this example, someone is being asked to hang up a party dress after trying it on. The speaker is likely asking this to avoid having the dress become wrinkled.