It's not a common word in English, though you might see it in some contexts like:
* French loanwords: You might see "quarante" used in some English words, like "quartet" (a group of four).
* French phrases: In English phrases borrowed from French, like "Quarante jours de carême" (Forty days of Lent).
If you're trying to understand a word or phrase in English, make sure to check if it's from another language!