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"Treinta" is a noun which is often translated as "thirty", and "son las nueve" is a phrase which is often translated as "it's nine o'clock". Learn more about the difference between "treinta" and "son las nueve" below.
el treinta(
treyn
-
tah
)A masculine noun is used with masculine articles and adjectives (e.g., el hombre guapo, el sol amarillo).
2. (number)
b. thirtieth (in dates)
El cumpleaños de mi padre es el treinta de noviembre.My father’s birthday is on the thirtieth of November.
son las nueve(
sohn
lahs
nweh
-
beh
)A phrase is a group of words commonly used together (e.g., once upon a time).
1. (general)
a. it's nine o'clock
Son las nueve de la noche y Alicia todavía no llegó.It's nine o'clock in the evening, and Alicia has not arrived yet.