Fran, (number/ # ) 2, Apartment Block 3. 

Or even 

Fran, Ap. # 2, Apartment Block 3.  (or "Block" for short).

Or "Apartment Building 3" (American way).

But, it´s advisable that when you send mail to another country that you put your address in the Brazilian way, it´s a Brazilian mailman that will bring your letter or parcel, and chances are that he doesn´t know the intrincacies of international addresses, mainly with Brazilian addresses (a novelty for him).

Even if you live in a "bloco" (kind of novelty here, perhaps it was influence of Canada) multi-family building and condos (that is the closest to the buildings and condos back here that we call "blocos").  Even so, we could put it in Portuguese.

Just a thought here, we know that it´s ultimately up to you after all.

https://www.englishexperts.com.br/forum/como-escrever-os-enderecos-em-ingles-t7160-10.html

https://www.quora.com/How-do-you-address-a-letter-with-an-apartment-number-in-the-U-K

https://en.wikipedia.org/wiki/Tower_block