Translation:Food is delicious.
그녀(는) 거기에있다. (geunyeoneun geogieissda.) She is there.
그들(은) 거기에있다. (geudeul-eun geogieissda.) They are there.
는 - (neun) is 은 - (eun) are
They are what they call subject/topic markers. 는 is usually placed after a vowel. 은 is usually placed after a consonant. These are the grammar rules for the two.
I hope this helped a bit.
So, why is this written as “음식은” and not “음식이”? And why was the last example for me written as “빵이” and not “빵은”? What’s the difference between using “-이” and “-은” in this case?
Generally speaking, if you're referring to a specific noun, you'll use the subject markers (이/가).
And most often, the topic markers (은/는) are used for general statements that can apply to all examples of a noun.
For ex: 빵이 맛없습니다. = "The bread tastes bad." (they don't like this bread)
"빵은 맛없습니다." would mean "Bread tastes bad." (they don't like bread)
But this isn't exactly set in stone. Sometimes, 은/는 are used for specific things.