Using this extension you will be able to read twitter tweets in any language!
Just click the "translate" link below the tweet and the translated text will pop up in front of you.
Please note: This extension is using Google translate API - which means you will need to provide an API key which can be obtained in the Google API console:
The api key needs to be typed in the options page of the extension where you need to select the target language for the translation. (the Google translate API detects the source language automatically so basically once you select the target language you are done!)