THis was very difficult to hear - it sounded as if it started with s
Hang on, what does this mean?
It's a response to a statement, usually expressing surprise and asking for confirmation. For example:
"He is not going back to school."
Guessing it's derived from "da vero" or "at/by/near true", or in English more or less "is that true?". Which in English we might express simply "Really?" as in "Is that really true"?