Please explain this syntax

Please explain this syntax.

I checked the syntax in the BO tool but it's very limited.

I have this line of code:

=count ([Orders] . [Order_ID] where ([Entered by Physician IND] = 1 ;  [Entered by Physician IND]))

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I don't understand what the  ";" is doing?

Is this statement a if/then?

Does it mean:

Count Order_id when physician IND = 1 or physician IND is null?