How can I make a condition for currently viewed language on a template file? I have a template called page-my-view.tpl.php that overrides a view page my-view.

I have directly put the title tags, description and h1 on this template file.

However I need different texts for these tags per language to avoid duplicated tags.

I have 2 languages on my site English and Japanese. 
Japanese is the default one with no prefix and English is with prefix "en".

So how can I make a condition on this template for currently viewed language?
In your template file global variable $language is avaible,with below properties

'language' => 'en',
'name' => 'English',
'native' => 'English',
'direction' => 0,
'enabled' => 1,
'plurals' => 0,
'formula' => '',
'domain' => '',
'prefix' => '',
'weight' => 0,
'javascript' => ''

You can achieve your jobs with something like this 
// if global variable $language  not avaible uncomment first line     

 //    global $language;
if ($language-&gt;language == 'en') {
   // do your desires
  }