WHOIS privacy allows you to hide your domain registration data from public. Your data will not be shown within a WHOIS request. This is good to be anonymous or prevent spam to WHOIS email addresses.
Your data will be sent to the registry or the provider of WHOIS privacy still to allow others to get in contact via a secure form.
For domains with the extension .com WHOIS privacy costs 9.99 € per year.
You can activate WHOIS privacy when ordering the domain or later in the management.