"These are our heads."
Translation:Is iad seo ár gcinn.
It rejects Seo iad ár gcinn.
A common way to introduce someone to a third party is to say for example Seo í Úna
Is iad seo ár gcinn is correct in Ulster Irish. In the other dialects, it should be Is iad ár gcinn iad seo, where the first iad is a subcomplement.
Two years later, but :) Is iad seo ár gcinn. seems the correct way to say it, and not only in Ulster Irish. This was what I answered based on what I had read on GnaG. It's again an example of copular sentence where the subject comes before the predicate because the subject is a demonstrative pronoun.
edit : The other sentence I was referring to is : Is é an fear sin a múinteoir. (here) In that example, the subject was not a demonstrative pronoun only, but held one, and in that case the subject also comes before the predicate.
In addition to being explained in the "Exceptions to the PSO rule" (link in the other comment thread), it's explained there, under "wenn das Subjekt ein Demonstrativpronomen ist bzw. führt.".