Using classic Outlook for Windows in business environments
Thanks @AndreaVironda-1776 for sharing your solution! You can accept your post as answer so that others reading this thread can benefit from your information.
By the way, if you are using an Exchange account, next when you meet this issue, you can try resetting the default folder names via OWA, go to Settings > Options > General > Region and time zone, change the language and select "Rename default folders so their names match the specified language":

Reference: Folder names are incorrect or displayed in an incorrect language in Outlook