By default, a calendar view will have one header above each column, with a default value based on the duration of the column. If you want to deviate from this default, you can use Time Headers. For example, you can create a week view with columns that span one hour, and a double time header: one for the day and one for each hour. This is shown in the screenshot below.
Create a Time Header
Navigate to the View record for which you want to modify the time headers.
Go to the Time Headers related list.
Fill out the details for the Time Header. For more detailed information on each field, see the Time Header field information table at the bottom of this article.
The time header should now appear for this View.
The Slot Label Format field on view is overwritten by time headers. If you want to add a time header that uses the Slot Label Format, pick 'Cell' for the Grouping.
Time Header field information
Time Header Name
The name of the Time Header. Descriptive names make it easier to identify them.
The amount of time that one Header will span on the calendar. Available options are:
Cell: the same size as one cell on the calendar.
Hour: one hour.
Day: one day.
Week: one week, leave the Header Label Format empty for week numbers.
Month: one month.
Quarter: one quarter, leave the Header Label Format empty for Q1, Q2 etc.