The Counting of the Omer is a preperation to the giving of the Torah because it stopps the race of time, and teaches us to live every day for himself.
Our Parasha lists the holidays; among them we find the counting of the Omer, the period we are currently in:
And from the day on which you bring the sheaf of elevation offering—the day after the sabbath—you shall count off seven weeks. They must be complete: you must count until the day after the seventh week—fifty days; then you shall bring an offering of new grain to the LORD. (Vayikra 23:15-16)
We are commanded to count forty-nine days from the beginning of the Omer, and to mark the fiftieth day as a holiday in its own right. The Torah does not mention the date of this holiday, but rather implies that it takes place at the end of the days of the Omer.
The Midrash in Vayikra Rabbah explains the meaning of counting the Omer according to a verse from Yirmiyahu:
Said Rabbi Elazar: It is written (Yirmiyahu 5:24) “They have not said to themselves Let us revere the LORD our God[…] Who keeps for our benefit The weeks appointed for harvest” - Who keeps us from bad winds and unwanted dews. And exactly when? During the seven weeks between Pessach and the Atzeret. (Vayikra Rabbah 28:3)
The uniqueness of these days is that they are the days of harvest, during which one goes to harvest the grain for which he worked all year. This work involves a lot of tension: one is occupied with how well the grain will give, and with fear that there will be a problem (with bad winds or unwanted dews) at the last moment that will cause the crops to fail. We can compare these weeks to the weeks before a wedding, in which after all the preparations and attempts to make everything succeed - even at the last minute there is always a fear of an unexpected event that will spoil the joy.
‘Mei HaShiloach’ explains that this is what the counting is meant for. Dealing with the fear and concern for the success of the grain is performed by counting - the person counts the days and thus fulfils a mitzvah, and according to the rule that “Rav Yosef said that with regard to a mitzva, at the time when one is engaged in its performance it protects one from misfortune” (Sotah 21 a), he will be saved from a bad fate. The solution that the counting presents, according to the explanation of ‘Mei HaShiloach’, is not only that the person will be immersed in expectations, but that he will also play an active role in the fulfilment of a mitzvah and thereby be protected.
In ‘Likutei Halachot’, R. Natan of Nemirov explains the meaning of counting the Omer:
And the main purpose of the count of the Omer is that one is to know that human days are counted, every single day.[…] For there are no days going who go void, God forbid. […] In the sense of “you shall count off seven weeks. They must be complete”[…] For seven Sabbaths allude to all of the human life. And this refers to the counting of the Omer, which is a beginning and preparation for receiving the Torah, to instruct that it is only possible to accept the Torah if one knows that the main thing is the present day that the person stands in. and not to be rejecting it from day to day[…] And this refers to “O, if you would but heed His charge this day” [היום אם בקולו תשמעו], meaning that if you wish to listen to his voice and accept the Torah, it is impossible to do so but if you accept “today”, knowing that the main thing is specifically this day. (Likutei Halachot, Hilchot Pikadon 4)
According to R. Natan, the preparation for the giving of the Torah by counting the Omer, is performed by man stopping the race of the days and standing still. ‘This day’ is the way to receive the Torah - when a person is aware that today is a day in itself, and understands the uniqueness of this day, he has the possibility to reach the inner essence that is to be found on this day. One can also see in R. Natan’s words a dealing with the basic state of counting the Omer: counting days increases one’s awareness of each passing day and thereby allows for us to see each day’s specific light; when a person goes towards the giving of the Torah, and knows that these days are approaching, he must know that each day stands by itself, to give it importance and not to annul it towards the future. Such a stance can protect the person from “bad winds and unwanted dews” that threaten him when he expects the giving of the Torah, and even when he harvests his grain.