Learn German: Wir lesen jetzt die E-Mail. - We are reading the email now.

Yes! Wir (we) is the subject doing the action, and die E-Mail is the direct object receiving the action (being read). However, because E-Mail is a feminine noun, its article is die. Feminine, neuter, and plural articles look exactly the same in the accusative case as they do in the basic nominative case. Only the masculine article changes from der to den.

Why does jetzt come before die E-Mail? Can I say Wir lesen die E-Mail jetzt?

In standard German word order, time words like jetzt (now) generally come right after the conjugated verb and before the direct object. While putting jetzt at the very end might be understood, the Time-before-Object rule makes your German sound much more natural.

The English translation says are reading, but doesn't lesen just mean read?

German does not have a separate continuous tense like English does with am/is/are doing. The phrase Wir lesen can mean either We read as a general habit, or We are reading right now. Adding the word jetzt (now) makes it perfectly clear that the action is happening at this very moment.

How do we know the gender of English loan words like E-Mail in German?