What does "up" in this context mean? I don't think it literally refers to a direction.
Native speaker’s answer
Rebecca
That's correct! "Up" in this context does not refer to the direction. Here the phrasal verb "eat up" is used, which means to eat all of something. Ex: Eat up! We're going to be late for work. Ex: Once you've eaten up your broccoli, we can have some ice cream.