What is the meaning of Yellow_card?

A yellow-coloured card, shown to a player (especially in association football) as a caution that he or she has committed a flagrant foul; a further such foul would result in a red card.

One of various yellow-colored cards used to verify the healthiness, vaccination status or other medical info of travelers.

A form to record safety concerns and adverse reactions to medicinal drugs.

A card sent out by a travelling dance or theatre company to request temporary personnel from a local labor union.

A yellow ticket.

A card given to British Army personnel during The Troubles.

Source: wiktionary.org