Person
Verbs in English are marked in limited fashion for person. Unlike some other European languages, person cannot generally be inferred from the conjugation attached to the verb. As a result, subject nouns and pronouns are generally required elements in English sentences for clarity's sake. Most regular verbs in English follow the paradigm exemplified below for the simple present of the verb "to listen":
1st sg. I listen 1st pl. We listen
2nd sg. You listen 2nd pl. You listen
3rd sg. He/she/it listens 3rd pl. They listen

Note: an archaic version of the second person singular is "thou listenest", and of the third person singular "he/she/it listeneth".