This is the 34th most frequent Greek word.
σήμερα
"Today."
In this sentence, 'σήμερα' is used as an adverb to specify the time frame, indicating that the statement is about the current day.
Σήμερα ο καιρός είναι πολύ ωραίος.
Today the weather is very nice.
In this example, 'σήμερα' serves to introduce the subject of the discussion, delineating the temporal setting for the given information.
Σήμερα είναι Τετάρτη, οπότε έχουμε μαθήματα.
Today is Wednesday, so we have classes.
Here, 'σήμερα' emphasizes the urgency or immediacy of the action, implying that it is important for the discussion to take place on the same day.