You can change your preferred language on the Wise website. To change it on the app, you'll need to change your phone's language settings.
Web and Android
Go on your name at the top
Go to Language and appearance
Select Language
Choose your language from the drop-down and Save
App
Go to your phone's settings and change the language. This will reflect on the app.
For iOS, you can also change the language in your Wise app from Settings.