I am guessing you are in a country where that language is the default. The web site automatically allocates a language based on where you connect from. The text appears to be Spanish, so in spain for the weekend perhaps? The links in the URL at the top of the web pages show the language and you can override the detected values with manual links. For instance. This link will be in US English as it is explicitly stated in the link (the official language of Mozilla is EN_US and is the base language others are translated from. Amusingly for me that means EN_GB is translated from US English.) https://support.mozilla.org/en-US/products/mozilla-account/accounts This link will be auto detected based on your location (IP address based so a VPN can cause havoc) hhttps://support.mozilla.org/products/mozilla-account/accounts This link will be in Spanish as it is explicitly stated in the link https://support.mozilla.org/es/products/mozilla-account/accounts All translations from English to other languages are not complete, so English text frequently pops up in untranslated articles.

@redacted, Are you still seeing this?