A noun clause is a group of words that contains a subject and a verb; however, it cannot stand alone as a sentence.
What you think doesn’t matter.
A noun clause can be used as the subject or the object in the following forms:
1. Noun as Subject
Example: What you think doesn’t matter
2. Noun as Object
Example: I don’t know what she say
A noun clause can begin with a question word, “whether” or “if”, a question word + TO infinitive, or “that”
1. with Question word
How she survive from that crash?
2. With “whether” or “if”
Whether he will go to her or not.
If He will go to her then she got accepted.
3. A question word + TO Invinitive
What to say to them, we didn’t know.
It pleased her parents that she worked hard for the whole term.
3. Do you know when they are coming?