To expose means to uncover or allow to be in the open air. If you take off your coat and expose your bare arms to the terrible cold, your tattoos might freeze off. (Note: We don’t actually know if this is physically possible.)
When you pronounce expose as it’s spelled, it can mean to leave out in the air, to put in peril (when you expose someone to danger), or to uncover. All of those examples are actions. However, when you pronounce it as though there is a French accent on the final "e," ex-poh-ZAY, it means the unmasking or exposure of something hidden (and usually bad or fraudulent), as when you watch an expose on 60 Minutes about the evils of frozen orange juice or some other toxic substance.