This command will add a variable text property to the selected text. This allows a text object to have different data that's easily updated, and is used for LED stats in the title block templates.

For example, in your Title Block Template, you might have a field for Date. Instead of having a static text object that you have to update every time you make a new layout, you can make this into Variable Text using the data variable $DATE, in which case the current date is automatically updated.

See Edit Variable Text for more information on this dialog and a list of the available data variables.