What does the uno card with no number just a color do?

In Uno, the card with just a color and no number is known as a "Wild" card. This card allows the player to change the current color in play to any color of their choice. Additionally, there is a "Wild Draw Four" card, which not only lets the player choose a new color but also forces the next player to draw four cards and skip their turn. Both cards provide strategic advantages in gameplay.