Bespoke software is written for a specific organisation. Instead of bending your business to fit a standard package, the screens, rules and reports are built around your own processes, your own terminology and the way your teams already work. Nothing is there that you do not need.
It is not always the right answer. If a standard product does the job well, use it. Bespoke work earns its place where the business has distinctive processes, several tools that do not talk to each other, or growth that off-the-shelf products keep getting in the way of. The key is to understand the process properly before anything is built.