This is the 2150th most frequent Portuguese word.
mina
"Mine" (e.g., excavation site for minerals) or "girl" (slang).
The word "mina" in this sentence means "mine", referring to a location where minerals like gold are extracted.
A mina de ouro foi explorada por séculos.
The gold mine was exploited for centuries.
Here, "mina" is used colloquially to mean "girl" or "girlfriend", often as informal slang in Brazilian Portuguese.
Ela é a minha mina, sempre ao meu lado.
She is my girl, always by my side.
In this context, "mina" refers to a natural water source, such as a spring, which is a less common usage but still proper in Portuguese.