"Owen yw e."
Translation:He is Owen.
"... ydy o" is the northern version of "... yw e" and they are both used in the emphatic semtence structure. You never say "Owen mae e/o" because "Mae" is never used in the emphatic. "Ydy" is also the question form using in both the north and the south e.g "Ydy Owen yn hoffi...?"
The notes for the section 'Present Tense 3' and elsewhere show that xxx yw e is the emphatic pattern used when identifying someone by their name, role, relationship, etc.