"My record speaks for itself."
Translation:Meu histórico fala por si só.
As a matter of fact, it means "itself" indeed. But in a different way. It's more used with this kind of catchphrase. "(Fala) Por si mesmo/Por si só" (Si mesmo = Itself - single noun, in this translation case.) But don't confuse it with "se"! (Both have the same sound, in some native sentences. E.g.: "Se ele falar comigo" - "Se" with the sound of "c" in English, not "ceh". It's a bit hard to explain.) It could be even more confusing, like... "Se ele fala por si mesmo..." (If it speaks by itself...) PM me if you got more questions, I'm a native speaker. I think I can be of help.