Ive got a weird message

I've got this message from my hosting server:

"A host, *ip address* has been locked out of the WordPress site at *my site address* ( until Saturday, May 13th, 2017 at 7:08:41 am UTC due to too many attempts to open a file that does not exist. You may login to the site to manually release the lock if necessary.

My site is still working though
What's could be the reason for this message?

Wordfence blocked the persons ip for attempted hacking/defacing your site.

someone tried hacking your site.
install a security plugin like wordfence to beef up site security.