When developing, one programming language (java, php, Solidity etc ..) How do i use it?

For example, you create a live streaming application, Web server: Nginx, Framework: Netty, Language: JAVA, Kotlin, PHP, JavaScript, C #, Solidity, Operating systems: Android, Ubuntu, Database: MariaDB, Aerospike, etc.

One framework for developing streaming services How do I use multiple operating systems, languages, and databases?

I am very nervous because I am a beginner.