As mentioned on the game jam page, how you interpret the theme is entirely up to you. You can take a literal approach, playing around with things or mechanics happening outside the visible screen. Or you might choose a more metaphorical or creative direction — maybe by breaking the fourth wall between the game and the player, or by crafting a mystery that focuses on what isn’t being shown.
These are just a few examples, but ultimately, how you choose to interpret 'Out of Frame' is completely up to you.