Audio files can contain a single audio channel or multiple audio channels. Final Cut Pro automatically groups audio channels into audio components according to how the channels are configured for the clip.
For example, many popular digital audio file formats, such as AAC and MP3, use interleaved stereo files, which don’t contain separate left and right channels. A stereo clip with interleaved left and right channels appears as a single audio component in the Audio inspector and the timeline. If you change the clip’s channel configuration from Stereo to Dual Mono, the channels appear as two separate audio components.
In Final Cut Pro, you can expand the audio portion of clips to view and edit audio components down to the individual channel level.