This means your work is waiting to be checked by Turnitin. It does not mean your work is waiting to be submitted. Your work is in the system, but not checked yet.

The first time you submit a piece of work (and the following 3 resubmissions), it can take between a few seconds and a few hours to return your report, but it may take significantly longer at peak hand-in times.  The forth resubmitted assignment will always take a minimum of 24 hours to return a report. 

If you have concerns, get in touch with your module tutor.