Copied from http://juerd.nl/site.plp/perladvice:

Here is an incomplete list of things that you will need to understand:

• An object is a reference to a blessed variable.
• A list is not the same as an array.
• There are three main contexts: void context, scalar context and list context.
• Things are named or anonymous.
• The language is Perl, the implementation is perl. Never write PERL.
• There are different operators for strings and numbers.
• Some operators perform short circuit logical operations, and these have high and low precedence versions.
• There are lexical variables, package global variables and package global variables that are always in the main namespace.
• Parameters are expected, arguments are passed.
• An operator is either a unary, binary or ternary operator, or a list operator.
• A statement consists of one or more expressions.
• You can use alternative delimiters to avoid the leaning toothpick syndrome.

If you understand all this, you have reached at least the level that I think is the absolute minimum required for you to call yourself a "Perl programmer".