In the second aliyah, the Torah gives the number of people counted in each tribe. Note, however, that G-d told Moshe not to count the Levites. The total number of Jews counted was a little more than 600,000 not counting the Levites. (Rashi says that a reason for not counting the Levites was that those people counted were destined to eventually die in the desert, but the Levites weren't to be included since they didn't take part in the sin of the chet ha-egel--the sin of the golden calf.) Here the Levites are given charge of dismantling, carrying, and erecting the Mishkan whenever it was to move, and they were to camp near it while all the other tribes camp in their own camps.