"Livia is a girl."
Translation:Livia est puella.
Livia was the wife of Augustus and the most powerful woman in the early Roman Empire. Livia is a common feminine given name in countries such as Italy and Romania.
French wikipedia adds:
Livia is the Latin name worn by an important family of ancient Rome. This name can be compared to the Latin adjective "lividus", which means "bluish" but also "envious" or "jealous", being then worn as a nickname.
In English "livid" is "dark bluish grey in colour".
I don't know this from reliable sources, but other users here on Duolingo say that "to be" sentences like this one are an exception. They are often in the order of S(ubject) V(erb) O(bject).
Please read the comments before writing the same thing, and if clarification is needed, make it into a question. User clemc0 wrote about it here, but his text was quite hard to understand, and I'd be glad to see a simpler way to express his knowledge, perhaps with a source.