The theme is what your game should be about or what should inspire your game, i.e. a theme could be "Unfair Platformer" and you'll have to make a game that incorporates that theme.
But, that means, we would know the theme at the start of the jam (14 days later), and then I need to make and submit a game based on the announced theme in the next two days (because the jam will end in two days after the start)? Or, I'm thinking something wrong??