If u want to know the capabilities and applications of EDK then u have to go through the docs available at Xilinx site at
**broken link removed**
As if u r just starting, EDK allows you to build a base system starting from chosing the processor u want to use for ur application, U can define the interfaces, buses and no. & I/O types etc., u want to build the system around. So, it's a complete development Kit which helps you to use the FPGA board in ur efficient way.