Hi Fernando, You can say "but are" (omitting that/they) or "but that are". "But that" is used for emphasis when something is certain or to mean "except." https://www.macmillandictionary.com/us/dictionary/american/no-doubt-question-but-that https://www.lexico.com/en/definition/but_that

Hi Fernando You can use either of these options -'Today we are going to talk about the pronunciation of 30 brands that exist in Brazil but are pronounced differently in English' (if there is no punctuation such as a dash or a comma after the word 'Brazil', it is fine to just use 'but'. - 'Today we are going to talk about the pronunciation of 30 brands that exist in Brazil but that are pronounced differently in English' I hope this helps Jimmy