WordPress websites are attacked by hackers and bots all the time. Many of these attacks target the login page. Thanks to plugins like WPS Hide Login, you can change the URL of the login form page to anything you want. It does so without actually renaming the file but by intercepting page requests.
Once you install the plugin, you should go to Settings > General to change your login URL. The plugin also supports WordPress networks. You can use it in conjunction with Limit Login Attempts to better protect your site. This is a free script.