It's likely a misspelling or a combination of phrases that don't make sense together.
Here's a breakdown of why it's incorrect:
* "Tu sabes" means "You know" (formal/informal)
* "No se" means "I don't know" or "It's not known"
* "Que estas diciendo" means "What you are saying"
Possible Corrections:
1. "Tu sabes que no sé qué estás diciendo" This means "You know that I don't know what you're saying"
2. "Tú sabes que no sé lo que estás diciendo" This means "You know that I don't know what you're saying" (more formal)
3. "No sé qué estás diciendo" This means "I don't know what you're saying"
4. "Sabes que no sé qué estás diciendo" This means "You know that I don't know what you're saying" (less formal)
5. "No sé de qué estás hablando" This means "I don't know what you're talking about"
The correct phrase depends on the intended meaning and context.