Usually you can tell by the context, which is missing when you have a single sentence. If you are asked, for example, "What does HE do for fun?", you would know from the context of the question that it should be "HE reads." Absent the context, you would not know if it is he/she/it. All are correct translations of legge without the context, or the subject pronoun.
I really appreciate all of these answers but my words are used like conjugations and present infinity I'm lost I am not grounded in grammar that way therefore these explanations confuse me even further! I'm sure I'm not the only one. So can you please answer in layman's terms and not English professor terms?