There is no language option in drupal 7 site When I hit  


  Administration > Configuration > Regional and language


There is no language option in drupal 7 site. Could I need to install modules? Which modules can I install?
It is be because you've installed Drupal with English. You can make Drupal Multi-lingual after it is installed, using the quick steps provided on HowTo: Basic Internationalization setup.

You can also have a look at the Multilingual guide for detailed information.