The focus of the book (as reflected in its title) is mainly on how to produce tonal harmony; less so on understanding it, e.g. it does not directly consider the interaction between harmony and melody. 'Part One' of the book is about 'Fundamentals', e g notes on the staff, scales etc. It is a clear and concise overview. However, it may cover the basics too quickly for someone with little or no knowledge of music theory. It might be better to start with an 'Everything', 'Dummies' or 'Idiot's' book on music theory.
While most textbooks on harmony include at least a few exercises, hardly any provide answers. This textbook provides lots of exercises (relatively) and a list of correct answers. This is particularly helpful for someone without a teacher. Without answers, a beginner may make frequent mistakes without being aware of it. Apart from careless mistakes, wrong answers sometimes reveal a lack of comprehension which may require a re-reading of some part of the textbook. Writing and analyzing harmony involve skills which require practice and feedback - for accuracy, retention and speed. I found the book very useful for its clarity and for its exercises ('self-tests' with answers). Incidentally, the 'Workbook' that accompanies the textbook has a lot more exercises but no answers. Unfortunately, this is typical of harmony workbooks (where completed worksheets are designed to be pulled out and submitted to a teacher). One workbook which does provide 'self-tests' with answers is Benward and Saker's "Workbook/ Music in Theory and Practice" (2 volumes). However their textbook (also 2 volumes) only provides 'assignments' (no answers).