For what is 'Geographic Target' I have explained on this thread at URL link; http://digitalbhoomi.in/forums/showthread.php?t=15501

How to set 'Geographic Target' for your blog?

Step 1 - Sign in to your Webmaster Tools account.

Step 2 - click your blog name/URL which is listed and verified.

Step 3 - Click 'Site Configuration' which is listed under the Dashboard column on the left-hand-side.

Step 4 - Click 'Settings'

Ensure that you see these array of boxes, tick for 'Target users in' and select the desired country (don't forget to click 'Save');

Settings

Geographic target........Target users in: (select the country)

Preferred domain.........tick for (Display URLs as your site name)

Crawl rate..................Your site has been assigned special crawl rate settings. You will not be able to change the crawl rate.

Parameter handling...You have configured 0 parameters.
If we don't do this, our site will probably receive less traffic from Google.