The Calendar can show the tasks in two different ways: in a Timeslot view or in a Task List view.

In a timeslot view, the leftmost column shows time scale, usually a row (also called slot) per hour, like here:

Using this view, it is very easy to see unoccupied slots that means free time, that hasn't been scheduled yet. The timeslot views therefore are extremely useful for scheduling purposes.

In a task list view, every day is shown as a rectangle and all tasks scheduled for this days are shown as a list inside the rectangle:

The task list views are therefore useful when you need oversee a long time span (like for a week or month) and see what tasks have been scheduled so far.

You can switch between the views using the Calendar toolbar:

The Day button will display the timeslot view for the currently selected day.

The Work Week button will display the timeslot view for the currently selected week.

The Week button will display the tasklist view for the currently selected week.

The Month button will display the tasklist view for the currently selected month.