Not sure what you mean by "jan report date". Do you mean an actual date or the text?
Can you show some sample data for better understanding?
As I understand it now, you have for example 4-1-2021 in A2 and 20-1-2021 in B2 (d-m-yyyy). In this case want a "jan report date" as a result.
=TEXT(B2,"mmm") & " report date"
But this can't be what you are looking for, right?