There are 5 statuses that Tasks can have from the creation of the Task, to the completion of it.
Pending: The task has been created by the task manager and is waiting for the freelancer to accept it.
Ongoing: The task has been accepted by the freelancer and work is in progress.
Awaiting review: It means the freelancer has finished his work and marked the Task as done. You can now review it and either mark it as Complete or switch it back to Ongoing if incomplete.
Completed: The task has been marked as done by the task manager, meaning that all work has been finished. Moreover, if autogenerated invoices are enabled on your account, an invoice is going to be automatically submitted once the task is marked as complete.
Updated: The task has been updated after the freelancer accepted it and is waiting for the freelancer to accept the changes.
Canceled: The task has been canceled by the task manager.
Declined: The task has been rejected by the freelancer.