The title carries significance at several levels. First, the film was conceived as a reaction to the sight of a man on a beach with a radio listening to the song Brazil. Second, the word represents the unknowable unattainable utopic existence which always lays beyond the realm of the possible. This is understood at perhaps two levels. The most obvious being the song itself, which reappears throughout the film. If you listen to the song you will hear that the mood represents the type of transcendently perfect existence the protagonist (and you, right?) dreams of. Also, the lyrics mimic well what is going on at the narrative level of the film, and what the protagonist (and by extension you while you're phenomenologically stuck at the level of the protagonist, right?) dreams of as his paradoxically unrealizable future. Third, the title is referencing the fact that during much of the 20th century the country of Brazil mimicked a great deal of the practices portrayed in the film. For example, forcing people to finance their own torture and murder at the hands of the state through a private credit line was taken from actual practices taking place in Brazil. Fourth, the title represents the fact that Brazil is the real life motivation behind both the hell and the utopia of the film. The State seen in the film is largely mimicking the State of Brazil, while the song which represents his ultimate unknowable unattainable utopic existence is in fact about Brazil. His paradise is his hell, and it is inescapable (unless you watched the Love Conquers All version, then yeah forget all this analysis).
Worth mentioning, it was originally going to be called 1984½, a reference to the two largest influences on the film: 1984 and 8½. If you like Brazil and haven't seen the latter, I highly recommend it.