IDE stands for integrated development environment. As the name suggests, this helps in getting some sort of a structure to our project.
Also, the IDE generally has plug-ins for tools that we would want to use as part of our project. Like a plug-in for cucumber-jvm in our case.
For the purpose of this book, we have chosen to use the community edition of IntelliJ. The other possible options is Eclipse.
People comfortable in eclipse should be able to use the same and readily apply the concepts dealt with in the book henceforth.