These docs are for an old release. Info on upgrading to v4

resources (as an array)

Tells the calendar to display resources from an array input.

$('#calendar').fullCalendar({
  resources: [
    {
      id: 'a',
      title: 'Room A'
    },
    {
      id: 'b',
      title: 'Room B'
    }
  ]
});

The id property is the most important because it allows associating events with resources. See the Resource Object spec for a full list of fields.