Socrates' discussion with Meno begins as Meno asks whether virtue can be taught. Meno suggests that it may be a result of practice or an inherent trait. Socrates answers by reminding Meno that Meno's own countrymen, the Thessalians, have recently gained a reputation for wisdom, due chiefly to the rising fame of Gorgias (a Sophist teacher). Gorgias, Socrates says, has taught people "to give a bold and grand answer to any question you may be asked, as experts are likely to do."
Athenians, on the other hand, do not claim to be able to answer such questions, says Socrates, noting that he himself is certainly among the ignorant. We should note that Socrates' modesty here is somewhat false, at least in the context of the dialogue that is to follow. For Socrates (and for Plato), it is much better to know that one does not know than "boldly and grandly" to claim knowledge when one is in fact ignorant. Thus, Socrates' modesty simply sets up Meno, the Thessalians, Gorgias, and the Sophists in general for a fall later on in the elenchus.
Socrates adds to his admission of ignorance the statement that he has not yet met anyone who knows what virtue is (though he qualifies this statement with regard to Gorgias, claiming not to remember his meeting with him clearly). This claim astonishes Meno, who moves quickly, at Socrates' behest, to give a definition of virtue. Meno says that there are different virtues for men (managing public affairs, helping friends, harming enemies, and protecting oneself), for women (managing the home, protecting possessions, and being submissive to one's husband), and for children, slaves, the elderly, and so on.
This, of course, is not a definition but a list of different kinds of virtue. Socrates points this error out with a metaphor about Meno's "swarm" of virtues being like a swarm of bees. The bees differ in size and shape, but "do not differ from one and other in being bees." In other words, Socrates is after the definitive characteristics of virtue in general, the "form" (eidos) of virtue. This idea of forms, which suggests that there is an ideal, non-physical model for each kind of thing, will eventually play a major role in Plato's dialogues. Here, the term is used sparingly, and Plato seems to be thinking of forms as somehow inherent in each physical thing rather than as separated in some mental or divine realm.
In addition to the bees metaphor, Socrates also uses qualities like health and strength to show Meno that he is asking after the single form common to all kinds of virtue (strength in a man, for example, is the same thing as it is in a woman, regardless of how much of it is present).
Meno, however, is still somewhat unsure what Socrates is getting at. This persistent confusion should remind us of the originality of Socrates' and Plato's thought at the time (ideas that are now commonplace to us). The idea that the term "virtue" must refer to one thing in all of its individual examples (i.e., the idea of a definition) is quite different from the ancient Greek conception of virtue as various kinds of success in worldly affairs.