She flips the board over to represent a parallel dimension—later known as the Upside Down—and places the "Will the Wise" token on the black underside to show he is hiding.
A key moment in the episode involves Eleven using a board to explain what happened to Will.
She places a figurine of the Demogorgon next to Will's piece to indicate he is being hunted by a monster. Secondary Storylines Full article: The Gothic Pasts of Stranger Things