Well, you still got time to prepare for the jam. Brackeys' has a lot of tutorials you can use to make any projects you want. On August 22nd, the jam starts and the theme is announce. You then have to make a game based on the theme. then on August 29th, it's submission day and you submit what you got. as simple as that. Though don't force yourself too much and risk your wellbeing. Do what you can, learn more and prepare for another game jam.