Howdy adolfo, welcome to the Monastery!
In general, you'll have better luck posting your question as a new top-level post in Seekers of Perl Wisdom. Also, while you're at it, please use <code> tags to format your code; see Writeup Formatting Tips for more.
Also: the particular solution to the "ordered combinations" problem here is a golfed solution, meaning that the aim was to use as few keystrokes as possible, at the expense of (among other things) readability, time and space complexity. Unless you're specifically interested in Perl golf, you're likely better off using a different solution.