A complete online business you can charge money for, handed over running.
A platform is not a website with a login. It is billing that cannot grant the same payment twice. Auth that keeps one tenant's data away from another. An admin surface the operator can actually work in. A deploy that survives a restart at three in the morning.
Those parts are where most builds stall, because they are not the interesting half. They are also the half that decides whether the business can run without the person who built it.
What you get at the end is a system that makes money on its own, without a team behind it to finish the job.
Turning a service into software that charges for itself. The operating parts are included, monitored and documented. The platform can run without the person who built it.