It's a custom template by Ihor Romanyshyn from freedom-loving Ukraine, made for own projects. This template is based on https://github.com/selivan/https-ssl-cert-check-zabbix script. The script must be placed at the ExternalScripts directory, usually defined in the /etc/zabbix/zabbix_server.conf file. Usually it's /usr/lib/zabbix/externalscripts, but can differ on your installation.
Feel free to ask me something about this. I'll try to make this template better and more useful soon.