Semiotic refers to all sign systems--of language and images--at work in a culture that functions as a "second-order language or text": semiotic refers to the system of all potential arbitrary and relational signifieds that signifiers represent. Meaning-making is the result of relational diadic signs used at any moment by any member of a culture in a system of signs to convey relational and differential meaning: in a system of signs, signs are understood by their relationships with other signs and differentially defined by what signs they are not.
This quote is meant to explain that a language in use is constantly reinventing itself through the creative process of its speakers, a normal process in a living language. Think for a moment about how we do make meaning. If I use the word "dog," I have a picture of a particular dog or dogs in my mind's eye. The person to whom I am speaking, or reading my words, is likely to have a very different picture in his or her mind. That person must make meaning somehow in the gap between my "picture" and his or hers. This is a semiotic process, to some degree, because the word "dog" is a symbol of something, and semiotics is the study of symbols, albeit a study that goes beyond language symbols. The creative part of the process, which really does take place on an everyday level, is how we manipulate language as symbols, to communicate meaning in fresh and original ways, while the person to whom we are communicating must also exercise some creativity, to understand the new way in which the symbol is being manipulated.
While the term "fiscal cliff" has been overused extensively in recent days, this is a good example of the creative process at work. We do use the word "cliff" as a metaphor or symbol, a literal falling from a great height and being hurt and a figurative rapid and damaging descent in some contexts. When we add the word "fiscal" to that, we are manipulating this symbol and metaphor to suggest a financial or monetary descent that will harm us. I would guess that many Americans do not grasp the details of this potential descent, but, nevertheless, most do "get the picture."
How we make meaning in these situations is an interesting process because we must figure out the attributes that are being emphasized in a new metaphor. For example, if, when presented with the word "cliff," I focused on the beautiful view or the difficulty in climbing to the top, I would have no understanding of the point of this metaphor. There is a creative leap not only in presenting a fresh use of language, but also a creative leap in selecting the proper attributes with which to make a new meaning.