How do I know whether I have a transferable business or just a profitable job?

While many businesses are transferable, they might not be transferable at the value the owner wants. In many smaller businesses, the primary value drivers are the client list and relationships. To know what the business will sell for, it takes knowing what the other party is interested in buying.
A large business might have people and processes that the other party wants to own. They might just have a cash-flowing asset that someone else wants to hold and maintain. Or they might have something small that is kind of valuable to the buyer. There can be benchmarks and industry standards to look at, but it all comes down to what a buyer is willing to pay for the business.
Unless the business is a decent size, the owner will likely have to continue to work for a handful of years to sell it at the price they hope. Many service related businesses will require some amount of time staying involved post-sale to get the highest exit price.

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