You can indicate which languages you would like your storefront to be available in. On the left is a list of all available languages. Use the drop-down list at the bottom-right to select a default language.
To make a language available, click on the green arrow to the left of the language you want to enable. The language will be moved to the "Enabled Languages" list.
Disable a language by clicking on the green arrow beside the enabled language. The language will be moved back to the list on the left, which displays all unassigned languages.
Click "apply" to save your changes.