OK, this is probably the coolest feature of the BBC micro:bit. It's a 5x5 matrix of little LEDs. 5 rows. 5 columns. 5x5=25. Right in the middle of the board.
Check them out:
With this 5x5 matrix of LEDs, you can do all sorts of neat things. Each one can be turned on and off individually. So you can draw patterns like hearts and smiley faces. There's even a way to scroll text messages across the display, like "HELLO WORLD!" or "MIND THE GAP!".