As Lughaidh's translation suggests, this can be viewed as a
cleft sentence if that helps you to fit in into a VSO framework[*]. From that point of view, the main difference between clefting in English and in Irish is that the copula is always optional in Irish. That is to say, "Is dath dearg atá air" is an acceptable variant form of a focused sentence like this, but the
is is frequently absent, as it is in the Rosetta Stone lesson.
Note that focussed sentences like this are often (always?) contrastive, as is generally the case with cleft sentences in English as well. ("It's red--not orange or purple--that is the colour of it.")
[*] Of course, syntactic analyses of Irish typically don't consider the copula to be a verb anyway, but that's a technicality of little use to the learner.