I mean it ìs the "part of speech that expresses action or being," but in this etymology(online) 'verb' seems to mean just word or call or command.

An etymology is often just a bare list of related words with minimal glosses. Latin verbum also meant 'saying, expression, phrase, sentence'. It was used by Roman grammarians to translate the Greek term rhēma) 'that which is said, spoken'. Aristotle divided words into two categories: ονομα (onoma) 'name; noun' and ρημα (rhēma) 'verb'. (link). Grammarians, then as now, tended to use existing words rather than coin new ones.

Ceci n'est pas un seing.