"Ella es una maestra estatal."
Translation:She is a teacher from the state.
Does this mean she's a teacher at a public school? The English sentence doesn't really make sense.
Well, it depends where you live. In, for instance, the USA, a public school is one funded by the public finances. In the UK it's just the opposite, a public school is an independent fee-paying school and those funded publicly are called state schools. The expression would be "She is a state school teacher."