Semiotics!

An understanding of semiotics in language helps us understand how figures of speech are created.




As discussed in the text, commercials make use of multiple connotations when selling their products.  The layering of ideas is what Charles Sanders Pierce called "unlimited semiosis," and what Howells and Negreiros were referring to in their discussion of how advertising fills "empty" signifiers with signification (or signifieds, or significance!)
We can use the methodology they describe for understanding visual codes.  Following the example of Roland Barthes, they pointed out how one can look for (a) Overtly communicated information, (b) Covertly conveyed information or ideas (what is signified), and (c) "What goes without saying," the information that is presumed to be common knowledge, or natural (such as Barthes' example of France's Colonial Imperialism).

Here is a fairly straight forward example:

This commercial for Fiat, uses more codes.

For an ad in an Art Magazine, artist Jeff Koons played with the codes of advertising and our knowledge of them: