Don't fully understand this one

Ok, so the description clearly says " A pawn is safe if another pawn can capture a unit on that square.". This paragraph is followed by a picture containing 2 chess boards, a blue pawn marked as 'safe' and a yellow pawn marked as 'unsafe'. The blue pawn in the picture to the right is NOT safe, because there are no other pawns around him. WTF??? Have I misinterpreted the rules here? If so, please explain them.