Au-pairs from the European Union (EU), the European Economic Area (EEA), and Switzerland can enter and work without a visa. They are not subject to any labour market restrictions.
Au-pairs from other countries (third countries) need a residence permit (visa or residence title).
The visa must be applied for at a German embassy or consulate before entering the country. In some cases, proof of health insurance is already required at this stage.
And don’t forget: A valid passport from your home country is required for entry and the entire stay.