About Condition Expressions
Condition expressions test for a wide range of task characteristics, including:

Current status or previous status

Priority

Input and output values

Escalation

Dates and times associated with the task

Current user
For example, this simple condition expression tests for a task status of active:
#{currentTask.taskInfo.status} == "active"

The
#{currentTask.taskInfo.status} portion was selected from the Add Field display.

The "equals" operator == was selected from the Add Operator display.

The status "active" was selected from the Add Field display.
This more complex statement tests for the expiration of an active task:
#{currentTask.taskInfo.status} == "active" &&
(#{System.currentDateTime} + (ExpirationThresholdDays * 86400000)) >
#{currentTask.taskInfo.expireDate}