The lane guidance feature was initially limited to the United States and China when iOS 11 was first released in September, but Apple has been working to expand it to additional countries. Recently, the feature was introduced in Finland, Hungary, Ireland, Poland, and Czech Republic.
With the addition of these five countries, lane guidance is available in a total of 19 countries: Australia, Austria, Belgium, Canada, China, Czech Republic, Finland, France, Germany, Hungary, Ireland, the Netherlands, New Zealand, South Africa, Poland, Sweden, Switzerland, the UK, and the United States.
The other major iOS 11 Maps feature, which adds speed limit information to the Maps app, remains limited to the United States and the UK at the current time.
A full list of Apple Maps feature availability by country can be found on Apple's website.