You may have to explain more for anyone to know what you are talking about. What prompted your question? Where are you seeing that?
Does "date of div/sep" mean date of divorce/separation?
What form are you filling out that asks for that? i.e., on what form is the "line 2b" you refer to? Or what topic?
If you don't get an answer in this user forum, we can tell you how to phone TurboTax Support during business hours.
I don't understand what div/sep means
It likely means divorce or separation.
Are you asking in regard to a date of an original divorce or separation agreement that is on the Form 1040 Schedule 1, Line 2b? i.e., is your issue the same as the threadowner's? If so, does the image and answer that @Critter-3 posted above address your situation?
Or is your issue in regard to div/sep something else?