On Screenshots - when you created this reprex, it saved to your clipboard all that text (formatted for github, stack overflow or discourse), so you just need to ctrl+v it into a new topic.
summarize converted your full faithful data frame into a data frame with a single value,
library(dplyr)
faithful %>%
summarise(
big_wait = max(waiting)
)
#> big_wait
#> 1 96
Created on 2019-04-16 by the reprex package (v0.2.1)
select is a way to select a subset of columns/variables from a data frame. Since summarized created a new data frame, with only big_wait column, (no eruption), you got the error 'eruption' not found.