Understanding the fundamentals of Zabbix is important to building a scalable and clean monitoring infrastructure. The Zabbix official documentation can be found here and it is good to read through. I have made some posts that explain things for a more general audience than the official documentation.
Zabbix Bare Basics – Explanation of basic Zabbix terms
Zabbix Hierarchy – Basic explanation of how Zabbix hierarchy structuring works
Templates in Zabbix – How templates are structured
Macros in Zabbix – How macros work
Groups in Zabbix – What groups are and why they are important