You should have a Python development environment available and be comfortable with programming Python at least to an intermediate level.
You should have some knowledge of descriptive statistics, linear algebra, and probability theory. If you are a data science or machine learning practitioner, you have the ideal background for approaching the problems in this book.
You will need to be able to run Python 3.5+ in order to use OpenAI Gym. You can either install Gym from pip or clone the Gym repository itself.