This is the 519th most frequent Russian word.
декабре
"Декабре" is the prepositional case of "декабрь," meaning "December" in English.
The word "декабре" is used as a prepositional case form of "December" to indicate a point in time.
Мы собираемся поехать в отпуск в декабре.
We are planning to go on vacation in December.
Here, "декабре" serves as the prepositional case to specify the time frame during which something happens.
В декабре дни становятся короче.
In December, the days become shorter.
"Декабре" operates as part of a prepositional phrase, 'в декабре,' describing when the holidays occur.