If you are asking about SAP BusinessObjects Profitability and Cost Management (PCM) then it is not a module of R/3. It has to be installed separately (https://websmp104.sap-ag.de/~form/sapnet?_SHORTKEY=00200797470000088668&_SCENARIO=01100035870000000202&)
SAP PCM is not a separate module and it is not a part of ERP or R/3. SAP PCM is an independent software which came to SAP's portfolio by acquisition of BusinessObjects. PCM was formerly ALG software (independent company) which was acquired by BusinessObjects and subsequently BOBJ was acquired by SAP.
This means PCM is licensed, procured and installed separately, independent of R/3. You can get more details and view a demo at http://www.sap.com/solutions/sapbusinessobjects/enterprise-performance-management/pcm/index.epx
Hope this helps.