Promotion

When a pawn advances to one of the five hexes at the far edges of the chess board, the player must exchange it for a piece of higher value, usually a queen.

drawing of the 3-pawn board with pawn promotion shown

White pawns promote at: a10, b10, c10, c9 and c8.
Black pawns promote at: a3, a2, a1, b1 and c1.