I thought isst meant eat.
In third person, yes. But you have to conjugate verbs in German. Just like in English you'd say she is and I am, although the verb is to be.
I entered "ich isst", but it turns out to be "ich esse". Can someone please explain the difference here? Thanks.
isst is eat for "He/She/It". esse is eat for "I"
This is correct, there is something called conjugation which means the verb changes along with the pronoun.
Think of it like the English word, "to be". One would say, I am. He is. They are. It means the same thing, but it's different depending on the person you are talking about.
In English, 'isst' would mean 'eats' and 'esse' would mean 'eat'.
So I understand why it would be esse instead of isst, but what would happen if it was "you eat"? Do you need to conjugate that as well?
Yes, you have:
You (singular) eat: Du isst
You (plural) eat: