Here's the correct translation:
Tú sabes que te amas: You know that you love yourself.
Here's why the original phrase was incorrect:
* Tú: The word "tú" is used for the informal "you."
* Sabes: The verb "saber" means "to know."
* Que: This is the conjunction "that."
* Te: This is the reflexive pronoun "yourself."
* Amas: The verb "amar" means "to love."