"Dewi Lingo ydy o."
Translation:He is Dewi Lingo.
Yes, most questions start with 'ydy' in the third person. However this is a special emphatic sentence we use for names (and also jobs), as introduced in Greetings 2, although we cheated a bit in Greetings 2 by not using the full form of the written verb only the shortened spoken version. So for the singular we would write ....'Dewi Lingo ydw i' (I am Dewi Lingo), 'Dewi Lingo wyt ti' (You are Dewi Lingo) and 'Dewi Lingo ydy o/e' (He is Dewi Lingo).