The current chapter introduces the concept of variables and types, covering single-element objects (numbers and characters) and collections (primarily vectors and tuples). At this early stage, we only scratch the surface of the topics. In particular, the chapter doesn't cover any object in depth, and even excludes important ones like dictionaries. The reason is pedagogical: I didn't want to overwhelm readers with details about objects or types, considering that core programmatic concepts like functions and for-loops haven't yet been introduced.
In light of this, Chapter 2 should be understood as a minimal background on objects, sufficient for progressing into the basics of working programmatically.
The main skills you should gain from Chapter 2 are:
familiarizing yourself with Julia's syntax, and
distinguishing between scalars (single-element objects) and collections.