What they are
A recurring plan, called a service agreement in the iPhone app and sometimes elsewhere, is ongoing won work: the weekly clean, the monthly pool service, the quarterly maintenance. It holds the schedule, the crew, the price and how often you bill.
Set them up in a browser under Settings, then Recurring Plans. On the iPhone they are under Service Agreements.
Visits
A plan generates visits automatically, on a rolling basis, so the next few are always on the calendar without anyone booking them.
A visit is a real job. It has tasks, photos, chat, completion and invoicing, the same as any other. What is different is that it does not clutter your sales board, because it is not work you are trying to win. You already won it.
Checklists
A plan can carry a checklist template, so every visit starts with the same list of what has to be done. This is the difference between a crew that knows the round and a crew that knows the round today.
Schedule and price
A plan holds one or more day and time rules, so an every-other-Tuesday-morning round is expressible without anyone booking each one.
The price and billing cadence live on the plan, so what you charge and how often you charge it are set once.
Starting one from work you already have
The easiest way to start is from a job you already do repeatedly, rather than from a blank form. The job already knows the customer, the property and the price, so the plan begins with the parts you would otherwise retype.