Lesson Two covers a variety of topics from pronunciation of letters and tones, to the format in which the language is written. It moves at a fast pace and it is important to rewatch the video (possibly several times) to ensure you understand all of the content given.
For the purpose of these lessons (Learn Xi'an) and the associated flashcards, it is most important that you under stand the pronunciation of letters and tones. You should be able to pronounce the difference between...
Britton pronounces these in the video at 9:37 (9 minutes, 37 seconds).
Important vocabulary words to study can be found at Learn Xi'an's flashcard tool.