A leads activity history will give you the documented calls, notes, tasks completed, and emails sent. This can be helpful if you are covering for another salesperson, have taken over a group of leads or are working old leads who may have lost contact with you.
To see the full history in the mobile app, select the Lead then touch the More Options icon.
Select Activity History from the list.
This will then show you all the activity for the lead.
Touch the Logged Call or Task to see more details.