From Carleton Moodle Docs
A label serves as a spacer on a Moodle course page.It can be used to add text,images, multimedia or code in between other resources in the different sections. It is a very versatile resource and can help to improve the appearance of a course if used thoughtfully. Banners or descriptions may be added to labels to distinguish between and highlight different areas.
On the other hand, over-use of multimedia (sound,video) in labels can slow down the loading of a course page.
(Example of a label with an embedded mp3 file)
Text, images and URLs can be embedded into labels by drag and drop See Using Label.