By default, a job that gets a ENDED_NOT_OK task will cause a workflow to block. This requires input from a user to remove the block so the workflow can continue. It is possible to skip a task in a workflow that would have otherwise blocked.
Example of blocked workflow:
The task in a workflow can be defined to handle a specific ended status. This can be done on the task that runs after the task that was blocked using the Time & Dependencies in the properties of that task.
In the example below, JOBS.WIN.SKIP is going to fail. On the next task, JOBS.WIN.SKIP.1, do a right click and choose 'Properties'. From here choose 'Time & Dependencies'. Set the status and choose the ELSE condition 'Skip task'. Now when this workflow is executed it will skip the task that would have previously blocked the workflow.