The data explorer is where you define the report you want. It is split between account reports and resource access reports. Most reports use the same core elements and some have additional options. Having a play with the controls won't do any harm, although very large reports may take some time to load.
Any report you generate can be saved or scheduled.
It is possible to generate reports that are both large and complex; when this happens up you may need to save it to your computer to work with it.
Dimensions are about how you want to break down your data
This refers to the smallest time that differences are measured over. Most reports will offer day or month granularity - some may .
Some reports offer hourly granularity, depending the subject and the age of the data, and because this has 24 times as many data points, the date range is limited to two weeks.
Start and end dates
These are inclusive and by necessity are based on UTC.
This allows you to see results over the current organisation or all the organisations below you. Permission set or Group breakdowns do not have an all organisations option as they are specific to one organisation.
This will The series are which data you want to show and these can vary by report as well e.g. Resource name, Account type. You can display up to 9 series in the timeline and chart views.
The mean value over the period.
Total and Unique
The total number of events and Where the unique data point appears it means the number of unique (distinct) accounts that generated them. For example there may be 3000 total authentications by 2300 unique users.
Unique is only available for authenticationsonly appears on authentication reports at the moment.
The difference between the values on the first and last dates of the period (that have data).