어서 뜨다

float; or scoop it out

뜨다 is a verb with several unrelated jobs and these lines show three. Floating or rising: oil holds air so it floats, empty it out and it rises, the organ that gives a fish buoyancy so it can float. Scooping liquid or food: go and fill the water jug, bring a bowl and scoop it out to eat, I'd never seen someone scoop a serving out for another person. And one line is eyes opening — 눈이 떠져서. The "-아서/-어서" in front just supplies the cause or the preceding step.