Please explain the chemical importance of salt in our body.?

It helps to regulate water flow into and out of cells among other things.

Here's a better explanation:

http://en.wikipedia.org/wiki/Sodium_chloride

I have high blood pressure, so I've read a lot about this. The average person eat about 5 times more than they are suposssed to. You ar suposed to eat 2.4 g each day. There are studies on people that don't consume any salt whatsoever, the lack of salt doesn't seem to affect them in any way.

Well, the short answer is because of the way the kidneys work, we would dehydrate without sodium. When the kidneys absorb sodium water follows it and is absorbed into the blood stream and functions as our blood plasma.

Also, cells funtion on a form of chemical energy called ATP. Sodium is used in the formation of ATP and also it is used in allowing the ATP to be used by cells.