Exposure lock is used when you take a meter reading off of something that is not the subject; there are times when you would rather meter offf of a mid tone like green leaves or grass. You point the lens at the grass and press the AEL button. The exposure is set for that mid toned subject.
The focus lock allows you to focus on the subject and then recompose. For example, you focus on a person and then move the camera so that the person is off centered in the fame rather than square in the center.

Thanks ronk II : but Can I use both at the same time : I mean lock the fouces and recopmse and Lock the meter on Mid tone Area Or I have to use Either one Only
and How to set it up

I'm not a Nikon user, so I cannot answer that. But you can use the Auto Expopsure Lock button and then use the shuter button to lock focus. Just press the shutter 1/2 way down and hold it there when you focus on the subject, reframe the subject and then press the shutter button all the way down. That will allow you to do both at the same time.

This seems the same in Nikon but Iam not sure if it works this way I mean how do I till If the AE lock is set up for Locking Exposure so I can use the shutter release for locking Focuse .... thanks very much I think it starts clearing Up a bit

Point the lens at the grass, as in my example, press the button and the exposure is locked.