The language that your customer will see in your checkout can be set up in your account.
Step 1: Register an account
Step 2: Configure language
In order to configure your language in checkout, first open the Checkout app. To do this, either click on the Checkout symbol under Business Apps or click on the Manage or Open button on the Checkout section.
On the left navigation bar, please select Settings and click on the Language tab.
You can either make your checkout available in one language only and thus force your customer to see the checkout in a certain language. Or you can enable multiple languages which will, based on the user agent of the customer, decide in which language the checkout is displayed to your customers. If the language of the customer is not available at payever, the default language option will be shown to the customer.