You've never skied before and it is your first lesson.
You can run straight down a nursery slope, but cannot yet hold a snowplough in order to reduce your speed or stop.
You can hold a snowplough and use it to control your speed and to stop. You may be aware of how to make a snowplough turn, but you cannot yet execute it consistently.
You can consistently make snowplough turns in both directions, and can stop on command.
You can traverse across the slope with skis parallel. To initiate your turns, you start with a snowplough, but you generally finish the turn with your skis parallel.
You are starting to adjust your pressure onto your skis, and the ski edge, to undertake basic parallel turns. You may occasionally revert to a snowplough to initiate your turn on steeper sections.
You can reliably make good, rhythmic parallel turns on all but very steep slopes. You understand how to use pressure, edge and foot turn in different combinations, to make different kinds of turns.