Business in a box describes a company that is ready to be understood by someone new. Its processes are written down, its systems hold the records, its roles and permissions are clear, and its numbers can be produced on request. An outsider can see how it works without having to ask the owner everything.
The benefit is practical for owners at any stage. A documented business is easier to run, delegate and improve, and it is far easier to hand over, whether that means new managers or a future sale. Whether a sale happens, and at what price, depends on many things; being organised simply removes avoidable obstacles.