The language can be changed in 2 different ways.

Change the language of your webbrowser

Since this procedure differs depending on your browser, you can find a list of common browser including links to the documentation:

Firefox: https://support.mozilla.org/en-US/kb/use-firefox-another-language

Google Chrome: https://support.google.com/chrome/answer/173424?co=GENIE.Platform%3DDesktop&hl=en

Change SharePoint Settings

You can personalize your SharePoint-Experience via the settings bar.

Step 1

Click on your username and then select "My Settings" from the drop-down menu.

Step 2

On the User Information page, click "My Language and Region".

Step 3

In the "Edit Details" window, you can change your SharePoint display language in the Language and Region field.