See the current Perl documentation for lib:English.

Here is our local, out-dated (pre-5.6) version:

English - use nice English (or awk) names for ugly punctuation variables

    use English;
    if ($ERRNO =~ /denied/) { ... }

This module provides aliases for the built-in variables whose names no one seems to like to read. Variables with side-effects which get triggered just by accessing them (like $0) will still be affected.

For those variables that have an awk version, both long and short English alternatives are provided. For example, the $/ variable can be referred to either $RS or $INPUT_RECORD_SEPARATOR if you are using the English module.

See perlvar for a complete list of these.