RStudio Cloud Map Primer summarise_all() question

Hi, in the final part of the map primer, we transpose a set of vectors and then transform them into a dataframe. We then summarize this dataframe into a tibble.

I was wondering, if I wanted to create a boxplot with ggplot2 for that exact tibble, how would I go about referencing the values for the x and y in the mapping?

Thanks a ton