WordPress can change the language of the words that are found in the PO and MO files located in the language directory. If the words are not found in the PO and MO files, it will stay the same and won’t be translated.
To change WordPress language, navigate your WP Dashboard to Settings > General.
You will be directed to the General Settings page. In this page, you have options to change the format of the time, date, email, tagline, etc,.
To change the language, look for Site Language. Change the language to what you would like, then click Save Changes to save and a loading icon will show. Once the loading icon is gone, WP should have changed its language.