lo único que sé es que

the only thing I know is that

→ lo
phrase Rare #52,253
the only thing I know is that Introduces something the speaker knows, often emphasizing that they know little else.
SP: Lo único que sé es que mañana tenemos que salir temprano.
EN: The only thing I know is that we have to leave early tomorrow.

Mira, lo único que sé es que no es mío.

Look, all I know is that it isn't mine.

— Marty Supremo (2025)

Lo único que sé es que vive en Berlín.

All I know is that he lives in Berlin.

Lo único que sé es que no es Iván Souto.

All I know is that it's not Iván Souto.

— Contratiempo (2017)