By default, the Mobile Time Tracker tracks time to Projects, Tasks, and Work-types. As a Mobile Time Tracker user, you need to select Project, Task, and Work-type before you Check in your time, using the slider. If you don't see any data in any of the drop downs, please contact your Salesforce Admin and ask him/her to add the required Projects, Tasks and Work-types to your organization.
If your company has configured Mobile Time Tracker to track time to other entities, you may see other items rather than Projects/Tasks/Work-types. You may see items such as Opportunities, Accounts, Cases, and Activities.