There is a filter to exclude non-English questions from the Hot Network Questions list. I'm not sure if the criteria for a question being English are still the same as in this eleven year old answer
a) The title has 2 or fewer non-English words (ignoring proper nouns)
b) The body is 75% English or more, by length
but today it failed for Por que Brasil em frances se escreve com E? Brésil on Portuguese.SE. Comparing the Hot Network Questions for Portuguese.SE with Spanish.SE or Italian.SE seems to suggest the filter is not enabled for Portuguese.SE; all sites regularly have questions not in English, but only on Portuguese.SE they qualify for HNQ.