RMarkdown Num Descriptive Stat

You appear to be trying to apply an R function to an Excel file.

First you need to read the Excel file into R and then apply the function. It looks like the functionm descr() is in the * summarytools* package which I do not have installed.

In any case try try something like this:

library("readxl")
dat1  <-     read_excel("Babies.xlsx")

descr(dat1)

or maybe

summary(dat1)

For general reference you may want to have a look at