Discard – the top cards that the dealer secretly demolishes from the deck into the bump, bringing them out of the game.
In such cases, they say that the croupier "burns the cards." Some prefer the "bury cards" option.
This measure is necessary to combat sharps who mark cards. If they put secret marks on the shirt, they will not be able to know which card will come to them or the dealer because the top sheet will go into the bump.
Also, the discard is used to create additional difficulties for card counters, correct dealer errors during the distribution and for other purposes.