"languages" is not found in regional settings I installed drupal commons 7.3.4,

I want to ADD an additional language. I try to follow this manual:

https://docs.acquia.com/articles/adding-another-language-your-drupal-7-site#language

go to Configuration &gt; Regional and language &gt; Languages


But there's no "Languages" section under "Regional settings"

I tried to enter the URL manually, but it brings me to "regional settings".

I enabled 


Locale 
content translation
Entity Translation 
Variable admin
Internationalization
...


i also flipped-flopped in the air, and prayed to budhha.

but there's no "Languages" in Regional settings.

What am I missing?
You're misreading the instructions (they're correct) and as a result, you're looking in the wrong place.  It is not in "Regional settings".

Start by clicking on "Configuration" on the admin toolbar. Then scroll down the page until you see a box with the heading "Regional and language".  Inside that box, below "Regional settings", you should see the link to "Languages"