What are the black and white images (with pink shapes) in the videos for?

Sometimes in the tutorial videos, Anna shows a version of the reference photo with certain parts changed to pink.

These images are used to show the area of the subject Anna's describing and is about to paint next.

Anna creates these images manually in Photoshop by selecting the areas and using a colour selection tool. So you need to be able to actually identify the different shapes of colour by eye in order to be able to do this the same way Anna does.

Some members use iPads / iPhones use the 'Value Study' app to isolate different tones in photographs: https://apps.apple.com/ca/app/value-study/id1546616127

As your artistic eye develops, you'll find you won't need to refer to diagrams like this to identify areas of tone. Seeing shapes of colour is something that will come automatically the more you paint. 

You can speed up that process by training your artistic eye. 

To do this, try placing your painting next to the reference photo, taking a step back and comparing the two. Also try turning both your painting and the photo upside down. By getting a different perspective on the composition you can often see these shapes much clearer than when you're up close.