As expatinaction says, it is more about menu planning and provisions ordering and sourcing.
All that "stuff" that just "turns" up, like milk, lemons, ice, newspapers, magazines, cabin amenities, cleaning materials, linen etc… That is all down to the FA. As is the loading, storages and presentation of everything, the cleaning and provisioning of the cabin. Washing all the dishes, glassed and silverware, or arranging for it to be done, laundry for the bedding and linens, and then, when you land, another hour or two on the plane making sure it is ready for immediate departure if required.
And, if on a multi city/day itinerary, arranging for your next lot of catering to be ordered and delivered and if different passengers, creating new menus for them etc. Plus, a lot of people will expect a little bit or errand running like personal shopping or something specific for the flight that you might have to go and find and search out in a city etc.