The Audio Library is the place where all audio data is stored. An audio entry within the library is typically attached to one lexical item. More specifically, it's attached to the item text or to one of the item's personal examples.
The contents of the Audio Library can be seen by opening the Audio Library dialog. Access to this dialog is found under the Tools menu. Here you can play, import, rename, delete, or simply view all audio entries in the library. Each entry is represented by a row in a table that has 3 columns. If the audio entry is currently attached to a lexical item then a paperclip is shown in the first column. The second column is the name given to the entry and the third column indicates the last time the entry was modified (i.e. imported or renamed).
To play, rename, or delete an audio entry, select it and click the corresponding button. To import a new audio file, simply click the Import button and find the file you want. Note that importing an audio file in this way does not attach it to a lexical item. See Attaching Audio for more on how to attach audio.
When an audio file is imported into the library then the audio entry's name is taken from the file name. When an audio entry is downloaded via the Download Audio Service then its name starts with "pl_af" followed by a number. Of course, this can be changed to be anything you want. It doesn't have to be unique.