Squarespace do not offer a Norwegian language option yet. You'll find details of the supported languages here, as well as details of the templates that support them (some Squarespace 7.0 templates only support English).
If your site has been built in English, there's a third-party service that you can use called Weglot. It can translate into 100 different languages including Norwegian and it is the only product I know that can successfully translate the checkout page.