This is the 512th most frequent Greek word.
ιούνιο
"Ιούνιο" means "June" in English.
Here, "Ιούνιο" is used as a noun identifying the specific month, June.
Ο Ιούνιος είναι ο πρώτος μήνας του καλοκαιριού.
June is the first month of summer.
In this sentence, "Ιούνιο" is used in the accusative case to indicate time.
Συνήθως τον Ιούνιο ο καιρός είναι ζεστός και ηλιόλουστος.
Usually in June, the weather is warm and sunny.
Here, "Ιούνιο" is again in the accusative case, specifying the time of action.