Hmm I'm not sure if hiding variables really helps, but
you could use perltidy to produce highlighted code (html), and setup the config such that variables (or other structures) have the backgroundcolor. (like JavaFan suggested)
But be aware that variable-sigils are important for the syntax.
Another approach could be to filter out or fold away inner structures by level of indentation.
If you are a total beginner activating tooltips when hovering over a command might help.
Using B::Deparse is a good tool to transform code into a standard representation, you can also activate extra parens to better understand the precedence rules applied.
Don't know much about Geany, but all of this could also be easily achieved using emacs.