1. means "
I don't know" in French.
2. also one of three answers you give your
French teacher when he/she asks you a question that
you don't know the answer too or are just too lazy to answer. (the others being "oui" and "non")
M/Mme/Mlle whoever: "Qu'est-ce qui s'est passé dans les chapitres que tu as lu hier?"
Student: "Ehh...je ne sais pas...mais c'était très intèressant?"
("What happened in the chapters that you read
yesterday?" "Eh...
I don't know...but it was very
interesting?")