This is the 14432nd most frequent Spanish word.
vísperas
The evening or day before an event, often a religious feast or celebration.
Here, 'vísperas' refers to the days or time shortly preceding Christmas celebrations.
Estamos en vísperas de las fiestas navideñas.
We are on the eve of the Christmas festivities.
In this sentence, 'vísperas' is used to denote the time shortly before her birthday.
En vísperas de su cumpleaños, decidió hacer una lista de deseos.
On the eve of her birthday, she decided to make a wish list.
In this context, 'vísperas' indicates the period leading up to the revolution, charged with significance or anticipation.