There is no meaning inwhat you say. The underlined clause is used as -

Noun clause বিভিন্নভাবে ব্যবহৃত হতে পারে। যেমন -

1. Noun Clause as Subject.
Ex - What is told by him is not clear.

2. Noun Clause as object of verb.
Ex - I know that he is an honest man.

3. Noun Clause as object of preposition.
Ex - There is no meaning in what you say.

4. Noun Clause as complement.
Ex - The fact is that he will never come.