Descript's label feature allows you to tag ranges of wordless media in the Script track. They provide a convenient way to assure that non-speech audio is labeled, which is essential for open and closed captions.
Labels can only be added to audio and video files that have been transcribed and placed in the main Timeline editor. If nothing happens after you select "Add label for range" try transcribing the file first. Please note that ranges cannot be placed on clips in the layer lane (above the script track), or on multitrack Sequences.
In the event that you need to remove/disassociate a label from a portion of your audio, switch to Correct Text mode by pressing Command + Option + E (MacOS) or Control + Alt + E (Windows), or Edit menu > Toggle Correct Text.
Highlight the range containing the label by clicking into the script just before the label and holding Shift + right arrow until the label is selected in the timeline, then press Delete. After a moment you will see that the label has been removed from that section of the timeline.
At this point, if there is some text that needs to be restored to the audio, you can now add it back in using Correct Text mode.