This is the 164th most frequent Spanish word.
enero
January.
Here, 'enero' is used as the subject of the sentence, referring to the month of January, specifically highlighting seasonal characteristics.
En enero, solemos tener mucho frío.
In January, we usually have very cold weather.
In this sentence, 'enero' is used as an object of the date construction, pinpointing a specific date in the calendar.
Mi cumpleaños es el 15 de enero.
My birthday is on January 15th.
Here, 'enero' functions as the subject that is described as the first month, identifying its position in the yearly sequence.