SLA Analytics is a feature that enables Jira users to see the SLA time against any issue field, e.g. you can see how many SLA time issues there were in a specific status or how long it has been assigned to different users.
SLA Analytics allows you to create your own issue-level statistics based on any field (standard and custom) and on the SLA Agreement.
The time shown in SLA Analytics is calculated against a selected SLA Agreement. It means that the time is counted only when the SLA time counter is active.
The reports are available in the SLA Analytics tab in the Activity section on the view issue screen. The statistics include activity from before the SLA Analytics was enabled.