The Italian word circa (cheer-kah) is not unfamiliar to English-speaking folks: we use it with dates to indicate something happened around the time we mention. In Italian, it has the same meaning, but with a couple more nuances.
Of course, the circa we like in English is not really Italian, but Latin, of course: we, just like many languages around the world, keep a thing or two from the old Romans’ language in our own idiom. Italians, though, we know it, have more Latin in theirs than they may like to admit, so it isn’t surprising to see they kept an adverb just the way it was, without even attempting at giving it an “Italiano makeover.” In any case, the word is first attested in the Italian language in 1321, which is, incidentally, the year Dante Alighieri left this earth to catch up with Virgil and Beatrice again. This time for eternity.
In Italian, circa means “about,” and embraces both meanings of this common English word: you can use it to say c’erano circa 1500 persone alla manifestazione (“There were about 1,500 words at the gathering”), or to make clear that ho bisogno di parlarti circa una questione di lavoro piuttosto importante (“I need to talk to you about some pretty important work matters”).
However, its use to indicate what something is about isn’t really common, especially when we speak, and often sounds a bit flouncy and unnatural. Go ahead and use it in writing though, if the register and the situation call for it!