Task and Schedule can be defined below:
Task: Servers to connect schedules with background task that should be run on that schedule. The task can be defined by type for schedule.
Schedule: Records in this table define a schedule according to which certain regular tasks may be Performed. They also indicate the next time at which the schedule will be triggered.
To simplify, These tables from repository helps us to understand about what/ why/how many schedules and background processes are tableau server executing.
These tables are very useful to identify underlying questions like when it is created, how many in total schedules are running on each site, which schedule takes longer time to run, heavy on performance, if any schedule is failed while running ?
It can be easily analyzed by connecting task, schedule, and site tables from repository.
To get more information about on each tables : https://tableau.github.io/tableau-data-dictionary/2021.4/data_dictionary.htm
To give an idea :
