Learn German: Der Mann arbeitet hier, und ich kenne ihn. - The man works here, and I know him.

ihn is the accusative direct object form of er (he). In the second part of the sentence, ich (I) is the subject doing the action, and the man is the one receiving it. Because he is the direct object, we must use ihn (him).

Could ihn ever translate to the English word it?

Yes! German pronouns match the gender of the noun they replace. Der Mann is masculine, so we use ihn (him). If we were talking about a masculine object instead, like an apple (der Apfel), we would still use ihn in the accusative, but in English we would call an apple it.

I learned that wissen means to know. Why does this sentence use kenne?

German has two verbs for knowing. wissen is used for knowing facts or information. kennen (used here as ich kenne) is used for being familiar with a person, place, or thing. Since you know the man, you must use kennen.

Why is the word order normal after the word und?

The word und (and) connects two independent sentences without affecting the word order of the second one. The second part just starts over with its own subject (ich) and verb (kenne) in the normal first and second positions.