PySpark is the collaboration of Apache Spark and Python. Apache Spark is an open-source cluster-computing framework, built around speed, ease of use, and streaming analytics whereas Python is a general-purpose, high-level programming language.
PySpark is a great language for data scientists to learn because it enables scalable analysis and ML pipelines. If you're already familiar with Python and Pandas, then much of your knowledge can be applied to Spark. I've shown how to perform some common operations with PySpark to bootstrap the learning process