You can run more than one restaurant from a single login on Business and Enterprise.
Adding one: Use the switcher at the top of the console — the box with your restaurant's name in it — and choose "Create new entity". You are taken through the same short setup as your first one.
What is separate: Everything that makes it a different restaurant: its own menu, web address, theme, opening hours, QR codes, analytics and billing. Staff you invite to one do not see the other unless you invite them there too.
Switching: The same switcher. Your place in the console is kept, so moving between two restaurants during a service is a tap rather than a login.
This is not the same as branches: Branches are several locations serving one menu — a chain where the food is the same and only the address and prices differ. Separate restaurants are for genuinely different places: a cafe and a pizzeria, or two brands under one owner. If you find yourself copying the same menu into both, you probably wanted branches.
On Starter: The option is not there. It is included on Business and Enterprise rather than sold separately, so the way to get it is to move up a plan.