It will change the law to explicitly clarify that journalists can protect their sources against government requests.
The definition used of journalist is:
a person who in the normal course of that person’s work may be given information by an informant in the expectation that the information may be published in a news medium
That would include myself as Kiwiblog is a news medium. I regularly receive information from members of the public, so it will be great to have clarified that I can protect those sources.