How she survived is a miracle. Here 'How she survived' is -

How she survived is a miracle. Here 'How she survived' is - Here, The underlined part is - Noun clause.
- It acts as the subject of the sentence.
- Since it is functioning as a noun (subject), and contains a subject ("she") and a verb ("survived"), it is a noun clause.

• A noun clause is a group of words that band together and act like a noun.
- Nouns clauses are used when a single word isn't enough.
- They're always dependent clauses.

• একটি বাক্যের চারটি স্থানে Noun clause বসতে পারে -
1. Subject হিসাবে,
যেমন: What will he do is uncertain.

2. Transitive verb এর object হিসেবে,
যেমন: I believe what you have said.

3. Linking verb এরপরে complement হিসাবে,
যেমন: The reason is why they are angry.

4. Preposition এরপরে,
যেমন: Listen to what they say.