Learn German: Jetzt lerne ich. - Now I am learning.

This is because of the "Verb Second" (V2) rule in German. In a standard statement, the verb must be the second idea in the sentence. Since the time word jetzt (now) is in the first position, the verb lerne must come exactly second. The subject ich (I) is then pushed to the third position.

Why does the verb lerne end in an -e here?

In German, regular verbs change their endings based on who is doing the action. The basic dictionary form of the verb is lernen (to learn). When you pair it with ich (I), you drop the -en and add an -e. So, lernen becomes ich lerne.

The translation says "I am learning." Where are the German words for "am" and "-ing"?

German doesn't have a separate "am doing" form like English does. The single present tense form ich lerne translates to both "I learn" and "I am learning". The context, especially the word jetzt (now), makes it completely clear that the action is happening right now.