It comes from "it serves". (Example: the restaurant (it) serves Mexican food). But "it" was omitted. But it may also be referred to a person, he or she
I graduated from high school in Argentina. People who speak English that live there use "Argentine" as the adjective. However, here it was not accepted!
"Serve comida argentina" One of the suggested correct answers is "We serve Argentinian food," I don't think "we" should be correct because of the translation of "servir," right?