An application can use these markers to be notified when a certain position is reached during playback. For example, you could use this information to synchronize content drawing with the audio being played, or to know which file is being played by a random container so that the correct subtitles can be displayed in your game.
For more information, refer to SDK help document, and search for "Integrating Markers".
..\Program Files\Audiokinetic\Wwise SDK vxxx\Help\
Also, you will find a code sample on how to use markers in:
..\Program Files\Audiokinetic\Wwise SDK vxxx\samples\IntegrationDemo\
The sample uses the markers for subtitles, but it is pretty much the same thing when using lip-sync. If you need the wav file name, you can store it in a marker and put it at the beginning of the file.