If you click on the “Day” button, your calendar will display one day of events. The initial day shown will be the current date.
If you click on the “Week” button, your calendar will display one week of events. The first day shown will be whatever day you designated as the first day of the week in your settings. By default, this is Sunday, so the Week view will start with the Sunday before the current date.
If you click on the “Month” button, your calendar will display one month of events. The initial month shown will be the current month.
If you click on the “Agenda” button, your calendar will display in text format, as a listing of events. This is helpful if you are viewing your calendar on a small screen, such as a smartphone. You can click on the “Look for more” link to have more events appear in the listing.
For all of these views, you can navigate forwards and backwards by clicking on the arrows pointing left and right in the upper left of the calendar window. If you navigate away from today, the “Today” button will become available and you can click on it to quickly return to the current date.
The tab between “Month” and “Agenda” will say “4 Days” by default. If you click on this tab, you will see 4 days of events, starting with the current day. You can change the "4 Days" to something else under the “Custom View" setting.