Shavua Tov. In today's Parsha, we learn that the preparation for the giving of the Torah on Mount Sinai was almost as important as the revelation itself.
Moshe Rabbeinu explained to the nation the special role they would have as a ממלכת כהנים וגוי קדוש, a nation of priests and a holy nation. Moshe asked the people if they understood what was being asked of them. On this occasion, they answered only with the word, "נעשה" and at a later time they said נעשה ונשמע.
The ספר התודעה explains that Moshe was telling them of their special יעוד, or destiny. The Jewish people, in effect, accepted their special יעוד in being a light unto the nations and having a different role to play than any other people.
Aside from the 613 Mitzvot that we are expected to observe, it has always been the job of the Jew to teach the world morality and right and wrong. Moshe explained that this was not going to be an easy task and could involve discrimination and suffering. Despite this, the people answered enthusiastically נעשה, that they accept this special role not only for themselves but for all future generations as well.