Vijesh,
If:
1. You have created work center capacities that are relevant for finite scheduling
and
2. These work centers are used in your routings
and
3. You run MRP with 'Lead time scheduling' parameter set
and
4. You schedule all your production orders
then CM01 and similar reports will display your available capacity and also the capacity load generated by your planned orders and production orders.
This is about the extent of what MRP can do with respect to capacity.
You can, however, also perform capacity leveling and capacity availability checking in ECC with additional non-MRP programs. Many companies are totally satisfied with these types of solutions, without ever using APO.
Here is a PDF doc that you might find interesting about SAP MRP/Capacity functionalities. Although it is a bit dated, PP hasn't changed all that much in the past 10 years.
http://help.sap.com/printdocu/core/print46c/en/data/pdf/PPCRPMRPMPS/PPCRP_MRPMPS.pdf
Best Regards,
DB49