[http://domainname.com] Site Lockout ...?

I got many emails with same message and different ips each time here is the message:

A host, xxx.xxx.xx.xxx(you can check the host at
http://ip-adress.com/ip_tracer/xxx.xxx.xx.xxx) has been locked out of the WordPress
site at http://domainname.com parmanently due to too many login
attempts. You may login to the site to manually release the lock if necessary.

what that does mean and how to stop this please??

Thanks you mates.

Someone might try to hack into your site. Do you got some security plugins?

No security plugins,it's a new site,what do you recommend?