One of the main reasons data analysts turn to R is for its strong graphic capabilities.
Creating a Graph provides an overview of creating and saving graphs in R.
The remainder of the section describes how to create basic graph types. These include density plots (histograms and kernel density plots), dot plots, bar charts (simple, stacked, grouped), line charts, pie charts (simple, annotated, 3D), boxplots (simple, notched, violin plots, bagplots) and Scatterplots (simple, with fit lines, scatterplot matrices, high density plots, and 3D plots).
The Advanced Graphs section describes how to customize and annotate graphs, and covers more statistically complex types of graphs.
To practice the basics of plotting in R interactively, try this course from DataCamp.