을지 알다

know what will happen

An embedded question "-(으)ㄹ지" — what or whether something will be — under 알다 "know". It says whether someone has that knowledge: we know what we'll call it, I know what I'm going to eat, he knows it'll be good. Very often it comes out negative: how could anyone know what they said, I can't know when my sound will finally come out. Note that with past 알았다 it can flip to "I assumed" rather than "I knew", which is what the first line is doing.