It means that this section contains example code, but is not actually part of the standard. From an operative point of view, this means that if it conflicts with anything else in the document, the "anything else" takes precedence.

> 'This section is non-normative'

Usually it is a concise or dramatic means to demonstrate something, but not adherent to the norms of that context.

For example, pouring petrol over a sofa and igniting it to demonstrate its fireproof attributes. Not normal behaviour but useful as a demonstration.

Normative is 'what should be normal', or 'ideally'—a normative argument is one pushing for a certain model of how things should be.