That's generally not such a great idea, even if you avoid the badness of having spaces in hash keys. Smashing strings together loses information that you may need later - e.g., you won't know if user "johara" used to be "jo hara" or "j ohara" (contrived, but you see the point.) Once you learn about references, you might want to consider a list of hashes (LoH) or a hash of hashes (HoH) to keep track of this kind of thing - e.g., "$user[0]->{Perry}{Steve} = 234" or "$user{0}{Perry}{Steve} = 234". That way, even if you get another "Perry, Steve", his unique number will keep him distinct from the previous one.

...but I'm wandering far afield. :) If you've just absolutely gotta do it the way you're describing, then at least separate the chunks with a delimiter that's not likely to occur in them - e.g., an underscore. My version of your script follows, with suggested modifications.

#!/usr/bin/perl
use strict;
use warnings;

# Might as well declare this early on and save some typing :)
my $s = "students.txt";

# *Always* check system operations for errors
open Fh, ">", $s or die "$s: $!\n";
print Fh "Perry*Steve*234\nSmith*Jane*456\nJones*Mary*567\n";
close Fh;

my (@bits, %pass);
# Don't guess at the error ahead of time - get the real story with '$!
+'
open Fh, "<", $s or die "$s: $!\n";
while(<Fh>) {
        @bits = split /\*/;
        $pass{join "_", @bits[0,1]} = $bits[2];
}

# Let's see what we got in the hash
printf "%s:\t%d\n", $_, $pass{$_} for sort keys %pass;
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-- 
Human history becomes more and more a race between education and catastrophe. -- HG Wells

Thank you for taking the time to write the comments, as you may know it makes learning it much much easier.
This honestly makes more sense than any other description I have ever had. Kinda feels strange to actually understand something that has been such a hard push to learn.

Thanks again okol!!!!