Some good answers above; I may not be able to add new specifics – having never worked in a fast food chain before (though I do have institutional kitchen and dining hall experience from way back in another life). The big thing for you now, since everything is all so new and probably strange, is to learn to prioritize, and how to prioritize.
So what you’ll want to ask about and know about the most are the issues that relate to safety and security. That’s “food safety” as well as “customer experience” safety (watching out for wet floors, for example, and spills of all kinds, and keeping the rest rooms clean – which may be one of your jobs from the start), but also the real life-and-death safety issues (as you may have been exposed to at the fry station, for example). So those are at the top of the priority list of “what to learn”: anything that has to do with safety of the employees, customers, delivery people, parking lots, etc. (even people who walk by on the street), and a close second to that would be the safety and protection of the building and equipment itself.
After that, I’d say (but defer to your management if they say otherwise), would be “security” of the building: closing and locking doors at the proper times, and when doors must be left unlocked during business hours, for example; keeping aisles and doorways clear and unobstructed to permit quick exit in case of fire (or even robbery; which is a thing that every franchisee is aware of), and proper handling of cash and other valuables.
Aside from that, as your training should indicate, there will be a list of “must do” items and probably a matching list of “must not do” things. Memorize those things, and then follow the instructions.
Above all else, your attitude will be key, as well as your ability to gradually manage that prioritization and memorization of must and must-not items. Everyone likes a puppy, and that’s what you’re going to be for awhile, but like all puppies, the quicker you can become housebroken (or in this case, used to the routine and able to figure out new things quickly, based on what you will already be learning), the more you will be appreciated.
And it’s never too soon to start saving for retirement. And I’m not kidding.