This is an R forum. Do you mean that you have read an Excel file into R?
If so you may find this useful FAQ: How to do a minimal reproducible example ( reprex ) for beginners
There are several ways to do what you want in R but here is an example of how to do it with the ggplot2 package using the built-it data set iris.
library(ggplot2)
ggplot(iris, aes(Sepal.Length, Sepal.Width)) + geom_point() +
geom_smooth(method = "loess")