Its best to call this function from within the after_setup_theme()
action hook i.e. after the setup, registration, and initialization actions of your theme have run.
function butter_setup(){
// This is where you would add support for theme features like
// post formats, feed links, etc
// ...
// Make theme available for translation.
load_theme_textdomain('butter', get_template_directory() . '/languages');
}
add_action('after_setup_theme', 'butter_setup');
Now add a directory named ‘languages’ in your theme directory.