Angel: I I I I
Am the Bird of America, the Bald Eagle,
Continental Principality,
LUMEN PHOSPHOR FLUOR CANDLE! (2.2.6)

It seems like the angel is saying that she is the spiritual essence, or energy, of America. Based on the other angels we meet later in the play, who all represent large geographic areas, we're guessing she represents all the other countries in North and South America too.