Dear student,

State of eligibility means that, from which state you have passed your class 12th board exams.

If you got alloted the seat in any round of josaa counseling, then you must have to upload the class 12th marksheet. On josaa offical site in the section of INSTRUCTIONS TO CANDIDATES , it is clearly mentioned you have to submit - class XII marksheet / state of eligibility proof . That means you have to submit class 12th marksheet for state of eligibility proof.
There is no format of state ot eligibility, just upload your class 12th marksheet.

Also check out the following offical link to know which document to upload :-
https://josaa.nic.in/webinfo/File/GetFile?FileId=23&LangId=P

Also check out the following link to know More about josaa 2020 counselling :-
https://engineering.careers360.com/articles/josaa-counselling