shoudn't it be "Jeg spiser en frugt"? as in "I eat a fruit" and not "I eat fruit"
No? Same as in English, you can say "I eat meat" or "I don't eat vegetables" to say that you do eat meat or don't eat vegetables in general (at any time.)
Depends on what youre trying to say. In this sentence it says I eat fruit which could mean I am eating fruit or I like to eat fruit something in that sense not I am eating a singular fruit
As an English person, I have a very challenging time saying "frugt" without laughing my eyes out.
en tomat er en frugt