Since you can create Power BI custom visuals using R, that means you'll be able to design a custom R-based chart, and make it available to people using Excel — even if they don't know how to use R themselves. There also many pre-defined custom visuals available, including some familiar R charts like decision trees, calendar heatmaps, and hexbin scatterplots.

For more details on how you'll be able to use custom R visuals in Excel, check out the blog post linked below.

PowerBI Blog: Excel announces new data visualization capabilities with Power BI custom visuals