Your summary page is private to you and allows you to get an overview of your total hours as well as a snapshot of top tags and applications used.
The Time Tracked in a Period (1) graph shows the total hours worked, hours posted, and hours not posted for the selected period (3). The Daily Summary shows the breakdown per day for the selected period (2). You can click on any bar in the daily summary to go to the timeline on that day.
Top Tags shows the total time (posted and unposted) for the top ten tags in the selected date range.
Top Apps shows the breakdown of apps used in the selected date range.