Since you are new to R, I'm going to give you a hand with your reprex this time.
You have to share your sample data on a copy/paste friendly format, the easiest way to do that is using datapasta package, so let's say your data frame is called df you would have to do this:
install.packages("datapasta") # This is only requiered if you dont have datapaste installed already
datapasta::df_paste(df)
# This output is what you have to paste in your post to share sample data
data.frame(stringsAsFactors=FALSE,
index = c(446, 447, 448, 449, 450),
period = c(446, 447, 448, 449, 450),
timestamp = c("0:13:41", "0:13:43", "0:13:43", "0:13:43", "0:13:45"),
duration = c(1.96, NA, NA, 1.973, NA),
location = c("120, 79", "110, 39", "10, 41", "111, 42", "2, 40")
)
Now that we have sample data, we can solve your problem
df <- data.frame(stringsAsFactors=FALSE,
index = c(446, 447, 448, 449, 450),
period = c(446, 447, 448, 449, 450),
timestamp = c("0:13:41", "0:13:43", "0:13:43", "0:13:43", "0:13:45"),
duration = c(1.96, NA, NA, 1.973, NA),
location = c("120, 79", "110, 39", "10, 41", "111, 42", "2, 40")
)
library(dplyr)
library(ggplot2)
library(tidyr)
df %>%
separate(location, sep = ",",into = c('x', 'y')) %>%
ggplot(aes(x = x, y = y)) +
geom_point() +
theme_bw()

Created on 2019-02-02 by the reprex package (v0.2.1)