The seventh day of Succot is known as הושענא רבה. The reason for this name is that on this day there are many (רבה) הושענות. Each day of Succot we circle the Bima one time, but on הושענא רבה, seven times, so that the word, רבה, really means, הרבה, many.
The custom of beating the ערבה, the willow, began with the later prophets, Chagai, Zechariah and Malachi. The willow, that does not possess a good smell or taste, symbolizes sin. We are literally “beating” the remaining sin we still need to drive away. It is a custom, so that no blessing is recited.
This is considered a solemn day, and some have the custom of staying up all night learning Torah. It is seen as the last opportunity for atonement before the final, “sealing of judgement” that began with Rosh Hashanah. It’s as if, the King, Hashem, is allowing one last opportunity for final arguments, before our fate is decided in the Heavenly courts. Therefore, the prayers are longer on Hashana Rabah, and there is a similar seriousness to these prayers, to those of Yom Kippur.
We are to also have in mind in our prayers, that we be granted sufficient rain during the coming year. May all of our prayers be granted for a healthy and happy new year.