This is what was retunred when I ran your code with perl -w:

Global symbol "$string" requires explicit package name at math1.pl lin
+e 10.
Execution of math1.pl aborted due to compilation errors.
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You would have found out the issue very easily by yourself, if you have warnings on.

What you want is an array, and it is a bad idea to do what you are trying to do (and I am not going down the eval path):

use strict;
use warnings;

my @strings = ("Jessy", "Bob", "Nancy");
for (@strings) {
    print $_, "\n";
}
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