Face cards is a widely used term that refers to specific playing cards. In a standard 52-card deck, face cards are jacks, queens, and kings.
They are called that because of their design. Namely, unlike other cards in a deck, jacks, queens, and kings depict people. While aces often receive “special treatment” in various card games, they are still considered regular cards, even though the ace of spades is one of the most beautifully designed playing cards.
One thing you should be aware of is that the term face cards is used in North America while those cards are called court cards in the UK. Furthermore, some face cards have their own special names.
For example, the king of diamonds, jack of hearts, and jack of spades are often called one-eyed royals, with the last two being called one-eyed jacks. In addition, the king of hearts and the king of diamonds are usually called suicide kings.