what are {{}} in php code example

Example 1: what is php

Q: What is PHP?
  
A: PHP is a general-purpose scripting for the scripting of web developments.
It was originally produced in 1994 by Rasmus Lerdorf, a Danish Canadian
programmer. The PHP Group is now producing the PHP reference implementation.
PHP used to stand for Personal Home Page, now it stands for Hypertext
Preprocessor.
  
Implementation language: C (primarily; some components C++)
Stable release: 8.0.2 / 4 February 2021; 4 days ago
Developer: The PHP Development Team, Zend Technologies
Typing discipline: Dynamic, weak since version 7.0: Gradual
Designed by: Rasmus Lerdorf
Memory limit: 128 megabytes

Example 2: what is php?

PHP stands for Hypertext Preprocessor. 
It is an open source server-side scripting language which is widely used for web development.
It supports many databases like MySQL, Oracle, Sybase, Solid, PostgreSQL, generic ODBC etc.