I read that line in a magazine, and it was used as an identity statement. Semiotics as I understand it comes from the field of communication, and it has to do with the semantics of signs. It asks the question, what does that sign say within a the accepted frame of reference or context.
It was interesting to me that the author was fascinated by the semiotics of clothes – or what a person is trying to communicate by the clothes that she wears. But it was used to highlight the responsibilities that one has in what one communicates.
What does your clothes say within a certain semantic range of meaning? And also, it will say different things in different contexts.