Activity Repeat Time shows the times at which a user repeats the same activity within a single session.
For example, if a user has viewed a single page 3 times in the same session, activity repeat time will show the timings at which the activity is repeated.
To look at the activity repeat time, navigate to Audience >> User Explorer.
You will see the list of user IDs who have visited your site.
Click any of the client IDs and you will be able to see the the total number of sessions listed.
Click any of the sessions to see which pages a user viewed during the session, the number of goals completed, the number of events and if there were any e-commerce transactions.
‘Last view’ is the time when a user last viewed the page.’Activity repeat’ is the number of times the page is viewed and the ‘activity repeat time’ shows the previous times at which the same page was viewed.
Understanding User Explorer in Google Analytics will give you an overview about the user explorer feature.