Most of Perl error message is clear and can be easily guessed out, but some not.
You can find a complete list of Perl's error messages and warnings with explanatory text in the perldiag manpage.
You can also use the splain program (distributed with Perl) to explain the error messages:
perl program 2>diag.out splain [-v] [-p] diag.out
or change your program to explain the messages for you:
use diagnostics -verbose;