This is the 754th most frequent Finnish word.
marraskuun
"November" (possessive form: "of November").
In this sentence, 'marraskuun' is a genitive case of 'marraskuu' (November), indicating possession or association, describing the evenings belonging to November.
Marraskuun illat ovat pimeitä ja kylmiä.
November evenings are dark and cold.
In this instance, 'marraskuun' points to a specific time within the month of November, showing the genitive case used to denote the starting point of referenced time.
Marraskuun alussa lehdet ovat jo pudonneet.
At the beginning of November, the leaves have already fallen.
Here, 'marraskuun' specifies the celebrations, identifying them as related to November.