* "You gusta tú sonrisa": This part is incorrect. "Gusta" is used for things you like, but it requires a direct object pronoun. It should be "Me gusta tu sonrisa" which means "I like your smile."
* "Porque tu es bonita": This part is also grammatically incorrect. "Tu" should be "tú" with an accent mark, and "es" should be "eres". It should be "porque tú eres bonita", meaning "because you are beautiful".
Corrected Sentence:
"Me gusta tu sonrisa porque tú eres bonita"
Translation:
"I like your smile because you are beautiful."