Полный русско-английский словарь
That is, i.e., that is to say, in other words
1. that is to say; (как поправка, уточнение) I (you, etc. ) mean; ~ вы ошиблись you mean, you made a mistake; 2. (выражает удивление) what do you mean?; ~, как — не знаешь? what do you mean, you dont́ know?