Learn German: Wie alt ist das Kind? - How old is the child?

Yes, wie translates to "how". Just like in English, you can put it right next to an adjective to ask about a specific quality. Here we use Wie alt (How old), but you could also ask Wie groß...? (How big/tall...?).

Wait, I thought verbs had to be in position 2. Why is ist the third word here?

The verb ist actually is in position 2! In German sentence structure, a "position" is a block of information, not necessarily a single word. The entire question phrase Wie alt counts as block number 1. Therefore, the verb naturally takes the second slot.

Why is it das Kind? Isn't a child a male or female person?

Yes, but in German, grammatical gender doesn't always match biological gender. Das Kind is a neuter noun. That's why it is highly recommended to always learn a new noun together with its article (der, die, or das).

If I want to ask "How old are you?", do I use this exact same structure?

Yes, you do! While some languages phrase this as "How many years do you have?", German works exactly like English here. You would just swap out the verb and the subject: Wie alt bist du? (informal) or Wie alt sind Sie? (formal).