Screenshots are considered a bad practice here since we cant select and copy code from them, post formated code instead. Here is how to do it
I can't be sure this code is going to work for you since you are not providing a reproducible example and I'm not willing to download a file from that source.
library(tidyverse)
dat %>%
group_by(`Reaction List PT`) %>%
summarise(n = n()) %>%
mutate(`Reaction List PT` = str_replace(`Reaction List PT`, "\\(", "- "),
`Reaction List PT` = str_remove(`Reaction List PT`, "\\),")) %>%
separate(`Reaction List PT`,
into = c("Reaction_List_PT", "Duration",
"Outcome", "Seriousness_criteria"),
sep = " - ")
Since you are a newbie I strongly encourage you to learn how to ask your questions providing a proper REPRoducible EXample (reprex) illustrating your issue. This is not only the most effective way to ask for help it is also the most polite.