The R-ArcGIS Bridge was created to make working simultaneously in ArcGIS and R as seamless and easy as possible. The main benefit of using the bridge is that it allows you to have a workflow where you can map and perform analyses on your data in ArcGIS but then, if you need an analysis or wish to perform a data aggregation that is specific to R, you can easily transfer your data. In short, this works by using the arcgisbinding R package which allows you to directly communicate from ArcGIS to R (and vice versa) and transfer your ArcGIS data (be it shapefile, feature class, or table) into R as a data frame object. From here, the arcgisbinding package allows you to easily convert your data frame object into an sp object (the desired data object for perform spatial analysis in R with the sp package), such as a spatial points data frame or spatial lines data frame, etc. You can perform any R function you wish on your data and if you need to, easily transfer it back to an ArcGIS data type and directly write it to the ArcGIS project you are working with to map your new results or to continue your analysis workflow.
If you need an visual example, this is a demo video that shows the process I just described.
The bridge does assume you have working knowledge of R. There are a plethora of free resources online from the R community to help you do this. My personal favorites are those by Hadley Wickham (R for Data Science and Advanced R). He has written some of the most widely used R packages and is a real powerhouse in the R community. However, if you prefer a different learning format there are typically courses on Coursera, such as this one, along with other similar sites. Finally, if you are looking for specific resources on using R with ArcGIS, there are some web courses and a Learn Lesson scheduled to come out in February shortly before Dev Summit.
Hope this helps.
