Is there freedom of speech in Brazil?

In general, there is freedom of speech in Brazil. There is no problem in criticizing Zionism. There are legislations in Brazil that punish racism as a crime. As vague as it looks like. If you call a black "monkey" you can processed. In practice this legislation is only used against people who offend blacks. Jews are not considered an underprivileged group and you're not likely to be processed for criticizing jews, unless you do it in a very vulgar way. Now to call Zionism racism is in no way racism. Your colleague is exaggerating.