I'm guessing your data looks something like this:
set.seed(69)
df <- data.frame(month.sales = factor(rep(month.abb, 2), month.abb),
year = rep(2018:2019, each = 12),
sales = runif(24, 1, 2) * 100000)
df
#> month.sales year sales
#> 1 Jan 2018 114570.1
#> 2 Feb 2018 123197.1
#> 3 Mar 2018 166092.7
#> 4 Apr 2018 163214.1
#> 5 May 2018 109486.6
#> 6 Jun 2018 131429.8
#> 7 Jul 2018 167363.6
#> 8 Aug 2018 191097.6
#> 9 Sep 2018 127427.4
#> 10 Oct 2018 145360.1
#> 11 Nov 2018 134577.1
#> 12 Dec 2018 169486.6
#> 13 Jan 2019 168493.2
#> 14 Feb 2019 147552.5
#> 15 Mar 2019 139811.3
#> 16 Apr 2019 156351.2
#> 17 May 2019 199368.3
#> 18 Jun 2019 130953.6
#> 19 Jul 2019 148150.5
#> 20 Aug 2019 166307.3
#> 21 Sep 2019 121830.8
#> 22 Oct 2019 101838.1
#> 23 Nov 2019 109716.9
#> 24 Dec 2019 125407.9
In which case you can draw a line plot like this:
library(ggplot2)
ggplot(df, aes(x = month.sales, y = sales / 100000,
color = factor(year), group = factor(year))) +
geom_line()

Note that you need to add the group aesthetic so that ggplot doesn't automatically group your data points according to the factor levels on the x axis.
python? Can you post sample data? Please edit the question with the output ofdput(df). Or, if it is too big with the output ofdput(head(df, 20)).