PyEZ is a high-level Python implementation that integrates better with your existing Python code. By utilizing Python API, you can perform common operation and configuration tasks without the extensive knowledge of the Junos CLI.
Juniper maintains a comprehensive Junos PyEZ developer guide at https://www.juniper.net/techpubs/en_US/junos-pyez1.0/information-products/pathway-pages/junos-pyez-developer-guide.html#configuration on their technical library. If you are interested in using PyEZ, I would highly recommend at least a glance through the various topics on the guide.