Yes, is this simply that she has three meters of something (cloth, rope, wire, etc) or is this an idiomatic way of saying something specific (e.g. that she is ten feet tall)?
Maybe she has three tools for measuring quantities such as amps, kilowatt-hours, tyre pressure, etc....
In Romanian it means she is 3 metres tall. It's an incorrect translation in my view, as it means nothing in English - you can't have three metres.
I assumed it meant she was three metres tall, on the same basis that when speaking of age you say in Romanian one has a certain number of years, not is a certain number. But then how do you distinguish between being three metres tall and having three metres of something?
When the girl has three meters of something, say fabric, we'd say "Fata are trei metri de țesătură". The following syntax is the same as in English.