R is a software environment for statistical computing and graphics (https://www.r-project.org/). It is well established and scripting languages like python easily interface with its data structures (in fact, python library Pandas reproduces many of them), but R has its own universe of ideas and extensions as well.
One related application is RStudio (www.rstudio.com), which is intended to provide a graphical interface to R. RStudio itself is extended with packages like Shiny (https://shiny.rstudio.com/), to make it easier to build interactive web apps straight from RStudio.
R has its own scripting language, which is not python (clearly), but python can work with R data structures nonetheless.
The data structure within R (the ‘Data Frame’) is a rectangular (row, column) structure that forms the basis for many data applications.