This statement has many applications, including graphic design. Let me give you an example. You are working on a document for your employees (maybe it’s a human resources employee booklet) and you find a cute piece of clip art. You include it in your document because it’s cute and you think employees will think so, too.
Visual elements, such as images, can add to the visual impact of the document and break up the text to make the document easier (and maybe more enjoyable) to read. However, you should choose visual elements based on the content because visual elements should enhance the content (add value).
If you add a cute graphic that is simply cute but doesn’t add value to the document, you probably shouldn’t add it. Always look for something to ENHANCE the content and not complete with it.