The schedule flow is set up to run once a day. It compares the current date against a date in a List (e.g. date to complete a task), this is done with the "condition", dates are equal - reminder send, dates aren't equal - end the flow. The main challenge I had with this one was to set up dates to be in the same format.
You can also set it up to compare the current date vs date in a list e.g. +/- 1 month to send upfront notifications or late completion reminders etc.
Hope this helps