My single surname is Silva, which is a very common name in my country, Brazil.
The origins of Silva are not exactly known, but it is a portuguese last name spread over its colonies including Brazil.
There are many family names in Portugal which are also popular in Brasil such as: Oliveira, Pereira, Santos and many others.
When we first met someone, we usually use the first named preceded by a title and in formal presentations or business meetings, the last name preceded by a title.