Google Sandbox is generally used for websites which are newly launched and then arouse the suspicion of Google, usually by adding a large amount of new content in a very short period of time. This appears to Google as spam; and the Sandbox is essentially a spam filter which watches for suspicious activity, reasoning that a site which adds enormous numbers of new posts, pages and content instantly is probably filling itself with duplicate content or engaging in search engine spamming.

Google sand box effect It means your site won't be found anywhere in your targeted keywords.

Google Sandbox is a tool which helps to find keywords phrases.