"Yes, he wants to drink tea."

Translation: Ydy, mae e eisiau yfed te.

[EAML48]

The sentence "Ydy, mae o moyn yfed te" uses the North Wales "o" for "he" with "moyn", the S. Wales word for "want"

[llituro]

Why is it Ydy instead of Ydw?

[mizinamo]

Because it's "Yes, he..." and not "Yes, I....".

"ydy, ydw" etc. are not a single word meaning "yes"; literally, they are forms of "to be" (bod) that are used when responding to a question. So Welsh doesn't say "Are you cold? Yes." but "Are you cold? I am."

Thus for "I" you need a form "I am" (ydw); for "he" you need a form "he is" (ydy), etc.