Thanks for the password, now I see how you set up the Header, please have 3 containers, put the Image, Menu, and Language selector in separate containers. Set all 3 containers Self Flex preset to Fill Space Equally
Now, place the image on the first container and set the Horizontal to Start
Place the Menu in the second container and set the Horizontal to Center
Place the Language selector in the third container and set the Horizontal to End
You can watch this video to learn how Flexbox works.
Hope it helps,