μήνα

In a sentence

• Έμεινα στην Αθήνα για έναν μήνα.

  I stayed in Athens for a month.

  In this sentence, the word 'μήνα' refers to a duration of time, specifically 'a month' as an increment of time measure.

• Ο Ιανουάριος είναι ο πρώτος μήνας του έτους.

  January is the first month of the year.

  Here, 'μήνας' (using a different case form 'μήνα') signifies 'a month' as a division within a calendar year.

• Ποιος είναι ο αγαπημένος σου μήνας;

  What is your favorite month?

  In this question, 'μήνας' is used to signify 'a month' in the context of discussing preferences about time periods within the year.