Assuming that your site is not
kyortisdzheykob.ru then somebody is sending a HTTP request to your site where the Host header does not match your site, i.e. trying if your site will answer to a request for
http://kyortisdzheykob.ru/ even if your site is actually
A web site should only accept requests for the actually intended domains and should reject any other requests. Failing to do this means that it is vulnerable for attacks like DNS rebinding and depending on the configuration of the site maybe even for more attacks like being used as a proxy to access internal resources.
It looks like that your web server is configured to accept such request which is bad. Fortunately your Django application behind the web server has an additional protection against this misconfiguration in the form of the ALLOWED_HOSTS option and fortunately this options seems to have been set to sane values instead of allowing everything. This means that you don't have to worry for now about the log entry you see: it is only showing that Django successfully blocked a request which was wrong.
But you should better also fix the problem at your web server. How this is exactly done depends on your specific server. But it usually can be done by having virtual hosts for the specific domains the server should be for and then have a default configuration for everything else which simply rejects the request.