Here are some possibilities based on potential misspellings:
* Fallen arches: This refers to a condition where the arch of the foot flattens, causing pain and discomfort. It's a common foot problem.
* Full arches: This might describe a foot with a high arch, but it's not a widely used term.
To understand what "fullen arches" means, you need more context. Please provide the following information:
* Where did you see or hear this phrase? (e.g., a book, website, conversation)
* What was the context surrounding the phrase? (e.g., what were they talking about?)
With more context, I can give you a more accurate and helpful response.