"This is what is wrong with him."
Translation:Dyma beth sy'n bod arno fe.
Thank you. Though if sy is a relative, there's no finite verb in the sentence (bod = infinitive), which is grammatically puzzling. The notes only say Beth sy'n (bod) = what is. Later: I've found the answer in an old Teach Yourself book. It seems to be a combined relative AND a verbal form of bod, so sydd/sy = who is, that is, which is. That explains my question anyway!