"You know me" would be "me conoces" or "me conoce" or "ustedes me conocen" or "me conocéis." It all depends on to whom you are talking, and where you are. The last example (the vosotros form) is not used in most of Latin America, but is in some countries and in parts of Spain. You must know if it is a formal or informal useage, as well as singular or plural.
This is how u say it in spanish: que quieres saber?
Translation: Sabes español?
¿Sábes qué? = Do you know what?
¿Me conoces?
i didn't know that you speak spanish = no sabía que hablas español.
Yeah, I do...lol did you mean, How do you say, you know lots of Spanish? If that's the case, then you say,"Sabes mucho español".
Do you know about that is: Sabes de eso
how to say,you must know your child's weight or age in spanish.
No sé
Sabe usted.....
" Sabes que"
Ellos saben.