2 inboxes in same account outlook 2016

2 inboxes in same account outlook 2016

Hello,

I have set up my mailbox in outlook 2016. Now when I open Outlook I have the folder "inbox" and "Postvak In".
Postvak In is dutch for inbox and my mail client is English. How can I make sure that I will only have 1 inbox?

The content of both folders are the same and get synchronised from the server.