A more thorough explanation:

Best embodiment refers to the best way an inventor knows to work the invention described and claimed in a patent or patent application. It is also known as the best mode.

For a patent application to be valid, it must disclose the best mode known to the inventor at the time of filing. Failure to disclose the best mode can render a patent invalid.

For example, if an inventor creates a new type of car engine, they must disclose the best way to make and use the engine in their patent application. If they fail to do so, their patent may be invalidated.

The best embodiment requirement ensures that the public has access to the best version of the invention and that the inventor is not withholding important information.