friend of mine
Ella es amiga mía.
She is a friend of mine.
Digamos que es una vieja amiga mía.
Let's say she's an old friend of mine.
Ella es una nueva amiga mía.
She is a new friend of mine.
La que vivía aquí era amiga mía.
The one who lived here was a friend of mine.
Ella es una buena amiga mía.
She is a good friend of mine.