Dear Sir,
Document Splitting is activated when u want your inter unit 
entries to be posted automatically at the time of fi entry.
Thus it helps to avoid inter unit reconcillation.

Regards,
Pravin 
SAP FICO

What is interunit Entries? & Interunit Reconcilation.

Document Splitting is a new feature SAP to be able to 
bifurcate costs incurred in one Document for different 
accounting and controlling purposes.
e.g. - You import an Item from China for $100000. And you 
pay Freight from China to US for $5000. The total cost 
incurred becomes $105000. Now, You would want to settle the 
cost of freight in your book of accounts by Treating them 
as a seperate cost (Line Item) still pertaining to One 
Document (transaction). Based upon your configuration need, 
you will set up the document splitting.

Please correct if I am wrong.

Can anyone elaborate this question Document splitting plz?

Document splitting is part of New GL PCA.

As per New GL PCA there are two entry views one for Entry 
view and General Ledger view. In General Ledger view you 
can find the document splitting.

For example
Material purchased for two differant profit centers under 
One Invoice. 

Entry view
Expenses    Dr  100 Profit center 1
Expemses    Dr  100 Profit center 2
To
Vendor      Cr  200

General Ledger View
Expenses    Dr 100 Profit center 1
Expenses    Dr 100 Profit center 2
To
Payable     Cr 100 Profit center 1
Payable     Cr 100 Profit center 2

If you see the general ledger view you can find the object 
of document splitting. 

Under Business Area concept you can not find this facility

Hope this will clarify