"I eat it."
Translation:Jag äter det.
I think it depends to what you are referring to. If you say "do you see the cat (katten)? I love it (the cat))", you use "Jag älskar den" (because cat is an en-word), but if you refer to, say a house (ett hus), you would say det. If you don't know what you are referring to (e.g. "it" is raining), use det.
Hon dricker den - She drinks it. I think you are confused because of den/det. It's simple, look: we use DEN if we refer to EN word. En Lunch. Jag äter den (maybe i'm mistaken in tenses, but you got the point). If it's ETT word, we use DET. Ett Apple --> Jag älskar det