How do you get "i eat" out of mangio? Is this because of the mascuilne suffix "o". If so can someone explain why
It is because the verbs form changes depending on the subject, so you don't have to exactly state who you are talking about. For example, Mangio = "I eat", Mangia = "He/She/It Eats", Mangiamo = "We eat", and so on.
It's because the conjugation for the verb mangare. I eat= io mangio. The sentence could also be written like this: Io mangio una mela. But the writer chose to omit the pronoun.
No language translate perfectly to another. My mother language is spanish and i had a very hard time learning english but now i can manage pretty well. The main difference -among others- betwen english and spanish (and italian from what i see so far) is that english is simpler when conjugating verbs. From my point of view learning to conjugate in italian is far more easy to a spanish speaker than to an english speaker because of this difference.
Why can't it just be "Eat an apple"? "Mangio una mela" doesn't have the word "Io" at the beginning and so technically, there is no "I".
Well you see, the word "Mangio" already refers to yourself. Just as "Mangia" refers to he/she/it. It is just how verbs are in Italian, the form changes depending on the subject.