R is an open-source programming language widely used throughout academia for statistical modelling. It can be especially useful for unusual data distributions (e.g., Tweedie or Poisson distributions). More recently, it's been adapated by vendors to work on much larger datasets than it was originally intended for.
Because of its unique characteristics, most analytics vendors have sought to integrate R capability into their existing products rather than create some sort of proprietary alternative. Oracle isn't the only company that has added R functionality to its products: Teradata
Corp. and SAS
Institute Inc. are two other examples.