What is noun clauses containing relative clauses?

A noun clause is a group of Words that contains a subject and a verb but is an incomplete thought that can't stand on it's own.

A noun clause can perform the function of a noun as the subject of a sentence and the object of a verb or a preposition.

A clause is like a sentence that's within a sentence. A noun clause has the function of a noun in the main sentence.

For example:

"I like Jane."

"I" is the subject (a noun), "like" is the predicate (a verb), and "Jane" is the object (a noun).

We can substitute for the Word "Jane" (which is a noun) a noun clause, such as "that she is so intelligent."

"I like that she is intelligent."

The entire clause "that she is intelligent" serves the same function as the noun "Jane" did in the original sentence. Thus, it's a noun clause.