What does em mean in Latin?

em, a interjection, means “here is, see!; this is why”.

How do you pronounce em?

In classical Latin, [ˈẽː]; in ecclesiastical (church) Latin, [ˈɛm].

interjection

Classical[ˈẽː]Ecclesiastical[ˈɛm]

here is, see!; this is why
em tibi!here's for you! (a blow, beating)
Em tibi ― Quid tibi istunc tactiost? ― Quia Iuppiter iussit meus.c. 180 BCE, Plautus, Casina 2.6.53–54

em, i. q. eum, v. is

I. init.

em, interj., = hem, Ter. Ad. 5, 3, 4; Varr. R. R. 1, 2, 5; 1, 56.

em, interj., = en (freq. in Plaut. and Ter. in best MSS.), Plaut. Merc. 2, 2, 42; id. Bacch. 4, 8, 29; id. Trin. prol. 3 (v. Brix ad loc.); id. ib. 1, 2, 148; id. Most. 5, 2, 58; id. Men. 2, 1, 26; id. Am. 2, 2, 146 Ussing ad loc.; Ter. Eun. 3, 2, 6 al., v. en.

noun · neuter

em²

em n or f (indeclinable)

Classical[ˈẽː]Ecclesiastical[ˈɛm]