QUICK ANSWER
"Es la una" is a phrase which is often translated as "it's one o'clock", and "quince" is an adjective which is often translated as "fifteen". Learn more about the difference between "es la una" and "quince" below.
es la una(
ehs
lah
oo
-
nah
)A phrase is a group of words commonly used together (e.g., once upon a time).
1. (general)
a. it's one o'clock
Es la una de la mañana. ¡Ya duérmete!It's one o'clock in the morning. Go to sleep!
quince(
keen
-
seh
)An adjective is a word that describes a noun (e.g., the big dog).
A masculine noun is used with masculine articles and adjectives (e.g., el hombre guapo, el sol amarillo).
2. (number)
b. fifteenth (in dates)
A Julio César lo asesinaron el quince de marzo.Julius Caesar was assassinated on the fifteenth of March.
a. fifteenth birthday
Mariluz está deseando celebrar sus quince.Mariluz is looking forward to celebrating her fifteenth birthday.