welcome
Thank you for purchasing the MEAP for Terraform in Depth. To get the most out of this book you'll want to have some experience with running CLIs, a small amount of exposure to any programming language (even bash will do), and a little bit of networking wouldn't hurt (if you know what an IP address is you should be fine). This book tries to start with a simple enough foundation that anyone can dive into it. At the same time it contains a variety of tips and tools that I've accumulated over the years that even a Terraform expert should learn a few things.
This book starts with the basics. The first part of the book will give you an understanding of the foundations of the language, from the basic syntax up through creating modules and using the advanced programming features of Terraform. Once you get through this part of the book you should be able to define all of your infrastructure with Terraform and create reusable, easy to deploy instances of your projects. For product teams this is amazingly powerful, as it means you can develop features and bring test environments up and down at all. For infrastructure teams it means you can define standard reusable components that the rest of your company can reuse to launch and manage their own infrastructure.