Described by Merriam-Webster as "anything that has mysterious or unknown internal functions or mechanisms," the phrase black box has become increasingly common in recent years, mostly due to the proliferation of things it can describe. When you think about it, black boxes are all around us: Maybe you see them in algorithms that determine which content you push to learners, possibly in the processes your suppliers use to create learning content, and probably in pretty much anything that occurs at your local Department of Motor Vehicles.
For talent development, it's mostly a phrase to avoid. As in, you don't want your department to become a black box.
When leaders from other areas of the business don't understand how your team does what it does, you can't expect to have an easy time working with them. They may set unrealistic expectations, such as asking for six-month projects in six weeks. They may resist the performance support you've offered them after an ask for more training, even though the performance support is what they really need. They may just avoid you altogether.
Either way, it's best to share not only what you do, but how you do it with internal clients. They may not need all the details, but don't forget: It's not easy to work with a black box.