The following are a number of functions within WordPress that we utilized, with examples.
string __( string $text [, string $domain ])
Retrieves the translated string into the current locale. The
$domain is "default" by default, but when authoring your own plugin, you should define your own text domain.
print __('Hello', 'my_text_domain'); // Might print "Hola" in a Spanish speaking locale.
_e( $text, $domain )
Prints the translated string into the current locale. The result is the same as if you had done:
add_action( $event, $function_to_add, $priority, $accepted_args );
Hooks an action event to a user-defined callback function; normally, no values are returned from these callback ...