Ull-yo-ah would be the Spanish pronunciation, AFAIA.
But the Argentinian pronunciation is more like Uh-jo-ah, with the 'j' making the same sound as the 'g' in mirage.
It's more like the 's' in 'pleasure'. Us-hh-oah.
Both correct. The 's' in pleasure is the same as the 'g' in mirage.