When multiple languages are installed in odoo, language codes are added to the URL to load the different content. For example the English version of the site could have the following URL: https://my.example.com/en_US/contact-us
This code can be 'customized" in the odoo installation i.e. use 'en' instead of 'en_US', etc by entering as admin and going to 'my profile'; here you can click on the globe by the languages field and customize the specific language. The field that defines what is shown in the URL is "URL Code", modify it to your liking and save, the settingas are immediatley applied but take care that this could break any links that use the old setting.
So, assuming that we cahnged the URL Code from en_US to en, the firsl example URL will become: https://my.example.com/en/contact-us