descripe please !

Question

Define , what is it mean in php code

Answer 1

If you declare a variable in PHP, you can define it as many as you want, but can only be declared once

Answer 2

All programming languages have a variable that can be defined as much as you like but can only declare once.

$x;
$x = 10;
$x = 20;
echo x; //20

Answer 3

You mean it's declare once in one file php or what ?