Can someone please explain me the  below syntax being used in one of the data template xml ?

I need to understand specifically the SUM syntax being used here ?? How it is working, on what all values the sum is being carried out  ?

<group name="XUYTHG" source="Q_ABCD">
    <element name="EMP_NAME" value="NAME" />
    <element name="EMP_DOB" value="DOB" />
   <element name="EMP_SALARY" value="MONTH_SALARY" function="SUM()" />
   <element name="AMOUNT_BORROWED" value="AMT_BORROW" function="SUM()" />
   <element name="AMOUNT_CREDITED" value="AMT_CREDITED " function="SUM()" /> 

If you can prepare one SELECT statement for above XML, things will become very clear ?