How to pronounce Juulia?

JUU-lia
J is pronounced as y in you.
The vowel sound of double uu is a bit like the double oo in the onomatopoeia ‘boom’. English language doesn’t really have a corresponding sound in any actual word. The uu should resonate at the back of the mouth unlike the English double oo sound usually does.
Lia is rhymes with ‘diarrhea’