"You are very intelligent."
Translation:Dych chi'n ddeallus iawn.
It is the NW Wales pronunciation of dych chi, and appears in informal writing there quite often. It is also taught in some regional Welsh for Adults courses, which is why we include it in Duo. Unless you live in the area, just be aware of it.
Thanks. I live in southern England, actually, and never come across Welsh, except here.