An embedded question is a question inserted inside a sentence. In English, questions always have inversion (the verb goes before the subject), but embedded questions have no inversion because they are not real questions.

affirmative You are Joshua
interrogative Who are you?
embedded question I don't know who you are.  (we can't say I don't know who are you because I'm not asking a question)

An embedded question may go inside another question. In that case, the real question (the first) has inversion, and the embedded question (the second) doesn't One question = One inversion (never more):

question Where is Sofia?
embedded question Do you know where Sofia is?

Many languages use inversion for real questions and for embedded question, so if your language is like that, be careful.

MORE EXPAMPLES

When will you come here? I have no idea when you will come here
How do you open this? She wanted to know how you open that
Where did you go yesterday She asked me where I went the day before
What is John doing here I want to know what John is doing here
When did she learn how to ride? I can't remember when she learnt how to ride
Why do leaves change colour in autumn? I don't know why leaves change colour in autumn
What does your sister want? I don't know what my sister wants

In unit 1 we saw a song called "What's your name", by Usher. Listen to that song again and pay attention to a sentence he uses with an embedded question:

- What's your name? I wanna know who you are.  (wanna = want to)
- Who are you? question
- I wanna know who you are embedded question

Watch Usher's video: