In addition to checking it is safe to move out from the kerb into the traffic flow, what must you do?

The correct answer is: Signal for at least 3 seconds.

In New Zealand, when you are merging from the roadside into traffic, the law requires drivers to signal at least three seconds in advance, in addition to ensuring that it is safe to do so. The importance of this regulation lies in giving other road users enough time to notice that your vehicle is about to merge into traffic and to adjust their speed or position accordingly to avoid collisions. Ensuring you signal before merging is a fundamental practice to enhance road safety, helping to prevent potential accidents and reduce risks associated with sudden lane changes or unforeseen actions.