体言 (THỂ NGÔN) và 用言 (DỤNG NGÔN) hay "static words" và "active words" (words that can transform, that can modify)
Nouns, on the other hand, can't modify at all. You can't do anything with the last kana of a noun or any other part of a noun in terms of grammatical modification.
But you can add logical particles to a noun and you can also add the copula だ or です to a noun. So, we have two sets of words: the 用言, the active words which you can modify by changing the final kana and adding something but you can't add logical particles or the copula to these,
and nouns and also pronouns and other noun-like entities, 体言 or static words, which you can't modify but you can add logical particles or the copula.
So for example when we add the soft copula な to an adjectival noun like 綺麗/きれい we have 綺麗な, and 綺麗な is regarded as a unit in itself.
And that's obvious, because once you've attached the copula to it, we can in fact modify it. The copula has a て-form, which is で, so 綺麗な can become 綺麗で in order to conjoin it to something else.
We can also modify 綺麗だ into, say, 綺麗だった. So, once we attach the copula to a noun, we have a 用言, an active unit, and as I'm sure you have already worked out by now, this means that the three engines, the three possible ways of ending a sentence, are all 用言, or active units.
A deeper look into the particle で
Because the truth is not that で is absolutely restricted to verb-sentences, A-does-B sentences, although most of the time it is. What it's restricted to is clauses that modify 用言. And the 用言, as we know, can be a verb, but it can also be an adjective or even an adjectival noun-plus-copula.