On my MacBook Pro the date is shown like this:
I'd like to remove the word 'Chaitra' from the menu bar (Chaitra is a month of the Hindu calendar). How can I do that?
To change the format of the date, you want to go to your "Language and Text" settings. Click on the "Region" tab at the top, then go to the section under "Dates":
Click on the "Customize..." button, then you should see a whole drag and drop section where you can change how the date is displayed:
Go to System Preferences → Date & Time → Clock and uncheck Show Date.
To change the language used, go to System Preferences → Language & Region → Advanced and set Format Language to the language you want to use.