English has suffixes spelled "-le" and pronounced /əl/ with several meanings. However, they variously come from Old English -el, -ol, -ul, and -lian. Of these, only -lian has a vowel after the l.
Also, many other words are spelled this way. When I look up their etymologies, they often come from Old English words ending in "el," /əl/, which explains the modern pronunciation but not the spelling, or are borrowed from Old French words ending in "le" (like circle), which I understand would have been pronounced /lə/ in OF, which does not explain how they got their modern pronunciations. Other words, like battle, are borrowed from French or Latin words that had vowels before the "l," and must have been respelled since, the same as the OE origin words.
I suppose it could have come from later French, where "le" would be pronounced /l/, which is often unpronounceable in English and so would be approximated as /əl/, which may have already been pronounced as [l̩]. This would match British "re," I believe. However, it does not explain why so many other /əl/ words were respelled with "le," when the same did not happen with "er" words. It also does not explain why words borrowed from OF like circle now have /əl/ and not /lə/. I suppose it's possible so many words were respelled to match the French, but it seems strange that it would have only happened in this one ending.