Date-time data can be frustrating to work with in R. R commands for date-times are generally unintuitive and change depending on the type of date-time object being used. Moreover, the methods we use with date-times must be robust to time zones, leap days, daylight savings times, and other time related quirks, and R lacks these capabilities in some situations. Lubridate makes it easier to do the things R does with date-times and possible to do the things R does not.
If you are new to lubridate, the best place to start is the date and times chapter in R for data science.
# The easiest way to get lubridate is to install the whole tidyverse:
install.packages("tidyverse")
# Alternatively, install just lubridate:
install.packages("lubr