the "L" after a number denotes that is of class "integer" and not "numeric"
class(10L)
#> [1] "integer"
class(10)
#> [1] "numeric"
Created on 2021-12-10 by the reprex package (v2.0.1)
Also, I haven't manually written the "L"s, that part of the code comes from the sample data (in a copy/paste friendly format). That format is usually produced by the use of the dput() or datapasta::df_paste() functions.
Read this reprex guide to better understand the concept
A minimal reproducible example consists of the following items:
A minimal dataset, necessary to reproduce the issue
The minimal runnable code necessary to reproduce the issue, which can be run
on the given dataset, and including the necessary information on the used packages.
Let's quickly go over each one of these with examples: