number of gpu's

There is 1 device supporting CUDA

Device 0: “GeForce 8600 GTS”
Major revision number: 1
Minor revision number: 1
Total amount of global memory: 268173312 bytes
Total amount of constant memory: 65536 bytes
Total amount of shared memory per block: 16384 bytes
Total number of registers available per block: 8192
Warp size: 32
Maximum number of threads per block: 512
Maximum sizes of each dimension of a block: 512 x 512 x 64
Maximum sizes of each dimension of a grid: 65535 x 65535 x 1
Maximum memory pitch: 262144 bytes
Texture alignment: 256 bytes
Clock rate: 1458000 kilohertz

Test PASSED

this was the output of device query command, but as a newbie i am not getting what exactly is this output, can somebody explain every term used in here?
and where are gpu’s ?how many gpu’s are there in this system?

You should probably start off by reading some material from the CUDA U site: http://www.nvidia.com/object/cuda_education.html along with the CUDA Programming Guide.

Those resources should provide all of the information you need to get started.