Usually on Art Card
Similar to matt lamination, gloss lamination is a thin protective film overlay commonly used on art card to enhance it’s quality and appearance. Making a card more durable and offer some water resistance feature.
Gloss lamination gives richer brighter colour and a shinny glossy surface, however potentially giving you unwanted glare reflection under strong lights.
Not advise to be used on fancy/premium cards, because this will entirely blot out the unique texture and colour of premium paper, making it no difference from an ordinary art card.