Issues plotting in R

Hi, and welcome!

Please see the FAQ: What's a reproducible example (`reprex`) and how do I create one? Using a reprex, complete with representative data will attract quicker and more answers. Also, please see the homework policy.

See if this gets you back on track

iris %>% 
  group_by(Species) %>% 
  summarize(Sepal.Length_freq = mean(Sepal.Length)) %>% ggplot(aes(Species,Sepal.Length_freq)) + geom_col()

Created on 2020-03-08 by the reprex package (v0.3.0)