What Lyrics are should not be hard to understand. Either way: Lyrics are the words or text of a song. But how are Lyrics represented in files? This is where things get a bit more difficult.
In audio files, it is most likely that Lyric information is recorded and thus can be found somewhere in the file. If so, the information is usually not displayed when playing the audio file in a music player though. When checking the file, however, it may be that information about the Lyrics of the song contained in the file shows up.
For video files, the state is likely the same. Music videos, in particular, can contain hidden or stored away Lyrics information.
Why, however, can information about Lyrics also be found in image files? When creating a still image from a video containing Lyrics information, it may happen that this information is transferred or carried along in the process. In this case, for example, Lyrics information is also present in the still image file or animated GIF.
Lyrics information can also be stored in different languages. For example, Lyrics can be stored in the actual language of the song together with an, e.g., English translation. These are typically represented with respective language codes like “eng” for English or “deu” for German (“Deutsch”).