This is the 10th most frequent German word.
es
"Es" in German means "it" in English.
In this sentence, 'es' serves as a formal subject in an impersonal construction about the weather.
Es regnet heute stark.
It is raining heavily today.
Here, 'es' functions as a placeholder subject in an introductory clause.
Es ist wichtig, jeden Tag Deutsch zu lernen.
It is important to learn German every day.
In this case, 'es' acts as a direct object pronoun referring to an object previously mentioned in discourse.