A viola is a flower (“VI-ola”) or a musical instrument (“vee-OH-la”). The expression which means “behold!” is voila. It comes from a French expression literally meaning “look there!” In French it is spelled with a grave accent over the A, as voilà, but when it was adopted into English, it lost its accent. Such barbarous misspellings as “vwala” are even worse, caused by the reluctance of English speakers to believe that OI can represent the sound “wah,” as it usually does in French
“Wallah” is a Hindi word for a worker, and “Walla” is half of the name of the Washington State city of Walla Walla.