The word comes from the Spanish "hombre." The H in Spanish is silent; it isn't said. "Hombre" means "man" and is used just like we would say in English, "C'mon man!"
One could also spell it ÅMBRE, but not UMBRE, because, in Chamorro, U is pronounced like OO as in TamUning. You young folks out there are so used to seeing everything through English lenses that, when you see U, you think UH as in UNderstand.
Ombre is often used in combination with other words, like :
Ombre, pot fabot!
Or at the end of phrases, like :
Generally, ombre denotes a sign of exasperation. "I'm tired of you kidding around, wasting my time, let's get on with it, man!"