Hello wyt248er, and welcome to the Monastery!

The syntax $UTF8{Euro} = ...; is indeed a variable assignment, but the variable assigned to in this case is a member of a hash. You can see this yourself in two ways:

# Method 1: With an explicit declaration

use strict;
use Data::Dump;

my %v;    # Hash declaration
$v{u} = "hello";
print $v{u}, "\n";
dd %v;    # Show the contents of the hash
[download]

# Method 2: Without a declaration

# No "use strict" here!
use Data::Dump;

$v{u} = "hello";
print $v{u}, "\n";
dd %v;    # Show the contents of the hash
[download]

The first method declares the hash %v using the my keyword, as mandated by the use strict; pragma. This is good practice. The second method just uses the hash without first declaring it. This will work only if the use strict; pragma is not in effect. This is considered bad style in modern Perl.

Bear in mind that the Perl documentation has been around for some time, and may pre-date modern best practice. In any case, the code examples in the documentation are snippets only, not complete scripts.

Update: Added 2 code comments

Hope that helps,