Added some comments to help you out:

use 5.16.2;
use threads;
use Thread::Queue;

my @serverList = qw(one two three four five six); # Array to hold list
+ of servers that need to be updated

my $serverQueue = Thread::Queue->new( @serverList ); # Create a Thread
+::Queue, passing in the array of servers as items to queue (each serv
+er is queued as a single string)
$serverQueue->end; # Nothing else will be queued, so notify the queue 
+of this by ending it

my @threads = map { threads->new( \&worker ) } 1..4; # Create a suitab
+le number of threads that wont overload IO on the local server
$_->join for @threads; # Block here until all the threads have complet
+ed

say 'Back to main - Finished!'; # End of program

sub worker {
    my $tid = threads->tid; # Get the ID number of the thread
    while ( my $server = $serverQueue->dequeue_nb ) { # Dequeue the ne
+xt item from the queue, in a non-blocking fashion (will undef and fin
+ish loop once the queue is empty)
        say "I'm thread ID $tid and I'm processing server $server";
        sleep 1;
    }
    say "Thread ID $tid finished";
}
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