Hello Miro!
This text can be changed when creating and configuring the badge. By default, in the "Message" tab, the default message is loaded using the default language of the user creating the badge; however, you can edit it and adapt to your preferences. Besides, if your badge can be awarded by users with more than one language, you can use the multilanguage filter to create the badge content: https://docs.moodle.org/en/Multi-language_content_filter
I hope this helps you!
Cheers!