The closest would be:
"A girl is having a meal." 밥 usually carries the connotation of a regular meal, not just food.
Also, "A girl" is a better choice than "The girl" here.
It is because of a rather intricate differences between 가/이 and 은/는.
In short, 가/이 is used often for mentioning something for the first time, corresponding to "a".
(Although it is difficult to say for an isolated sentence like this)