Since WP Statistics 11.0, PHP 5.4 or above has been required. If you are using an older version of PHP it cannot understand the new syntax included in WP Statistics 11.0 and generates a parse error.
Your hosting provider should have a newer version of PHP available, sometimes you must activate it through your hosting control panel.
Since the last release of PHP 5.3 is over 2 years ago (Aug 2014) and is no longer supported or receiving security fixes, if your provider does not support a newer version you should probably be moving hosting providers.
If you have done an upgrade and you can no longer access your site due to the parse error you will have to manually delete the wp-statistics directory from your wordpress/wp-content/plugins directory, either through your hosting providers control panel or FTP.
You may also downgrade to WP Statistics 10.3 as a temporary measure, but no new fixes or features will be added to that version and you should move to a newer version of PHP as soon as possible. You can download the 10.3 here.