In Nintex for O365 and Nintex for SharePoint On-Premise, typically you will create a workflow and identify the task list that resides inside SharePoint. These tasks are then tracked and handled from these lists. In Nintex Workflow the tasks reside completely inside Nintex Workflow and are also handled in Nintex Workflow.
Tasks in Nintex Workflow
Individual Tasks
In Nintex Workflow you will have a tab called My Nintex, underneath this tab you can view all the active tasks that are assigned to you only, under the Dashboard.

All Workflow Tasks (Business Owners only)
If you are an assigned business owner to a workflow, you will be able to view all the tasks of any instance of the workflow under the Workflow tracking tab.
Steps:
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Select the workflow you want to delve into
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Select your date range for the instances you want to search
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Select the instance you want to delve into
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On the right-hand side click on Show individual responses
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You will then see all the tasks to whom they were assigned and what the status of the task is. From there you can also click on the 3 dot elispses to either Delegate or Override the active task.